This topic is most helpful for people that are trying to access as much as they can in different skill trees while remaining the most effective, or for people who are just trying to save a few points to put somewhere else.

Before I begin, I like to note that if you take the first 5 points in that skill tree, that is what is going to make you extremely effective at that skill, even without taking the other perks that come along with it. Although, you can only put all 5 points in 16 of the 18 skill trees.

Another note, I will say that perks in general can be useful, but ultimately what your character's attributes are going to be the dominant factor in what you want to be. For example, a good mage is going to have a lot of magicka, and a good warrior will be well balanced between health and stamina.

Also, I'm just keeping the notes short and simple. I'm purposely leaving out a lot of details to make this post as short and as sweet as possible. If you have details on something, feel free to share it, but I probably already knew it. Not to say someone else doesn't.

Next to the name of the skill tree, I'm going to post the most effective perks and keep it at a bare minimum of the ones you really need to make that skill tree effective.

Now, let's begin. I hope you found this information to be useful in sculpting your character.

COMBAT:

Smithing: None

Pros:
- Any crafting skill is worth taking, but Smithing is the least of the three.
- Smithing is good if you plan on making and improving armor and weapons.
- Smithing armor and weapons in general is typically more convenient.

Cons:
- You can find any kind of armor instead of using points to make it yourself.
- Smithing things you are going to use can be very expensive.
- Daedric and Dragon armor can be found in chests. Daedric armor can be made using the Atronach Forge in The College of Winterhold, so if you can hold out for a while, there's no need to use any perks in this tree.

Heavy Armor: Juggernaut (5), Well-Fitted (1)

Pros:
- Heavy Armor provides more protection
- The Conditioning perk in this tree is far more effective than the Unhindered perk in Light Armor.
- The Juggernaut, Well-Fitted, and Matching Set perks give you more bonus armor than Light Armor.

Cons:
- Heavy Armor slows you down and drains more stamina when sprinting.
- Heavy Armor only gives you a bit more protection than Light Armor.
- Most of the perks in this tree aren't worth taking, and you have to spend a lot of points on useless perks to reach the good ones.

Block: Shield Wall (1), Power Bash (1)

Pros:
- Elemental Protection is good for anybody who uses shields.
- Power Bash can be used with any weapon without a shield. (Bows, 2h Swords, etc.)
- Disarming Bash works great against bosses.

Cons:
- Deflect Arrows doesn't do anything unless it actually hits your shield.
- Shield Wall deludes itself from 20% to 40%
- Really, who would want to waste any points on blocking?

Two-Handed: Barbarian (5), Champion's Stance (1), Devastating Blow (1)

Pros:
- Two-Handed weapons deal more damage.
- Two-Handed weapons have more reach.
- The Barbarian and Devastating Blow perks give you more damage bonus than One-Handed.

Cons:
- Swinging speed is greatly reduced.
- Two-Handed weapons weigh more than One-Handed weapons.
- Putting perks in Two-Handed weapons eliminate any possibilities of effectively blocking or using dual weapons.

One-Handed: Armsman (5), Fighting Stance (1), Savage Strike (1)

Pros:
- One-Handed weapons allows you the option to use a shield, spell, and/or another One-Handed weapon.
- One-Handed weapons give you the option for more effective sneaking (Daggers).
- One-Handed weapons has the unique option of Dual Wielding perks.

Cons:
- One-Handed weapons do not deal as much damage as Two-Handed weapons.
- One-Handed perk bonuses are not as effective as Two-Handed weapons.

Archery: Overdraw (5), Eagle Eye (1), Power Shot (1)

Pros:
- Great for sneaking.
- Lighter than even One-Handed Weapons.
- The only skill tree with the ability to zoom in.

Cons:
- Unless you have the Quick Draw perk, bows are only effective in sneaking.
- Most of the skills in this tree aren't very helpful.

STEALTH:

Light Armor: Agile Defender (5), Custom Fit (1)

Pros:
- Light Armor lets you run faster than Heavy Armor, and use less stamina.
- Light Armor has a unique perk that allows your stamina to regenerate 50% faster.
- Light Armor weighs less than Heavy Armor

Cons:
- Elven and Glass armors look ugly on anyone but Elves.
- Light Armor offers less protection bonuses than Heavy Armor
- Light Armor's Unhindered perk is almost useless.

Sneak: Stealth (1), Backstab (1), Deadly Aim (1)

Pros:
- This tree is essential for anybody who wants to be stealthy.
- The Backstab, Deadly Aim and Assassin's Blade perks offer huge damage bonuses.
- Only one point in Stealth is needed for anybody who needs to sneak out of a bad situation.

Cons:
- Muffled Movement and Silence perks can be avoided with the Muffle enchantment on your boots.
- The Stealth perk deludes itself from 20%-40%

Lockpicking: None

Pros:
- Helps you pick locks if you are having trouble with it.
- The Quick Hands perk is good if you're having trouble breaking into places.
- The Golden Touch and Treasure Hunter perks are wonderful to have.

Cons:
- If you are spending any points in this skill tree, you're wasting your time.
- There is enough lockpicks to buy or find that you don't need to make locks easier.
- Lockpicking can be enchanted if you need assistance in picking locks.
- All the perks in this tree are useless for staying alive.
- Unless you completely svck at picking locks, AVOID THIS SKILL TREE.

Pickpocket: None

Pros:
- This skill tree will make picking pockets on the go much easier.
- The Extra Pockets perk gives you 100 extra carrying capacity. A good choice for anyone.
- The Poisoned perk gives you the ability to poison people without getting caught. Perfect for Dark Brotherhood assassinations.

Cons:
- You can enchant items to make your pickpocket skill better.
- All of the perks in this tree are useless for staying alive.
- Who would want to waste points on this anyway? Unless you're a thief...

Speech: None

Pros:
- Makes prices better (Combined with enchanting, you could get up to 69% better prices).
- Allows you to sell any kind of item to any merchant.
- Allows you to make more gold by investing into shops.
- Allows you to sell any stolen items to anybody.

Cons:
- Although they're convenient, these perks aren't very useful outside of towns and shops.
- Instead of wasting points on Haggling, just enchant a necklace that gives you almost 30% better prices.
- The Persuasion and Intimidation perks can be avoided by leveling up your speech.

Alchemy: Alchemist (5), Physician (1), Benefactor (1)

Pros:
- This skill tree is a must-have for any player that brews potions.
- The Alchemist perk makes your potions and poisons twice as strong.
- You can make a potion for any situation you need (except for stronger potions)
- You can make a lot of money without having to spend any. (Giant's Toe, Creep Cluster, Bear Claw)

Cons:
- You have to either find or buy the ingredients in order to make the potion you need.

MAGIC:

Illusion: Novice-Master (5), Dual Casting (1), Animage (1), Kindred Mage (1), Quiet Casting (1)

Pros:
- The Illusion skill tree is excellent for crowd control.
- Many of the Illusion spells help you in a variety of different ways.
- Dual Casting illusion spells allows you to double the level of the spell and it stacks with all of the other perks.
- This skill tree is a must-have for any mages that play on Master difficulty.

Cons:
- You don't really need this skill tree if you play below Adept difficulty.
- The spells cost a handful of magicka to use.
- In order to be effective with them, you have to have your Illusion spell ready before the fight even starts.

Conjuration: Novice-Master (5), Summoner (1), Atromancy (1), Elemental Potency (1), Twin Souls (1)

Pros:
- You can summon monsters for a variety of reasons.
- This skill tree is a must-have if you play as a mage on Master difficulty.
- Two or more monsters alongside with a companion, and the enemy won't be able to touch you.
- Having monsters are fun! The possibilities are endless.

Cons:
- Most of the perks in this skill tree are useless.
- Summoning costs a lot of magicka, which can leave you out of magicka during the fight.
- Necromancers have to take up Dual Casting to be more effective with their zombies.
- Necromancers have to have a corpse before summoning anything.
- Mystic Binding is useless even if you have 5 ranks in Armsman. A daedric sword is better.

Destruction: Novice-Master (5), Dual Casting (1), Impact (1)

Pros:
- Destruction is obviously a must-have for mages.
- Destruction Magic is more effective when fighting against elemental creatures.
- The Impact perk makes using Destruction magic much easier.
- The Intense Flames perk is very humorous to watch, especially if they run off a cliff.

Cons:
- Most of the perks in this skill tree are useless.
- There's no need to put any points in this tree if you intend to get robes/armor with 100% destruction/restoration enchantment, which is the best option for a mage.
- It takes a whopping six perk points to become 50% more effective with each type of spell.

Restoration: Novice-Master (5), Regeneration (1), Necromage (1)

Pros:
- Restoration is obviously a must-have for mages.
- Restoration is highly effective against undead.
- The Necromage perk used by a vampire will give that person an extra 25% bonus to enchanting.
- The only skill tree that is used to heal yourself or your team mates without using potions.

Cons:
- Most of the perks in this skill tree are useless.
- There's no need to put any points in this tree if you intend to get robes/armor with 100% destruction/restoration enchantment, which is the best option for a mage.

Alteration: Novice-Master (5), Magic Resistance (3), Stability (1)

Pros:
- This tree has passive skills that can be useful for anybody.
- Alteration magic has a variety of spells that help in various situations.
- Alteration magic is the best line to a mage's defense.
- If you mix wearing armor with alteration's defensive spells, you will get a huge armor bonus.
- Almost all of the spells in alteration are fun to use in one way or another.

Cons:
- Ineffective to waste magic if you're already wearing armor.
- Spells cost a lot of magicka to use.

Enchanting: Enchanter (5), Insightful Enchanter (1), Corpus Enchanter (1), Extra Effect (1)

Pros:
- This is probably the most useful skill tree in the entire game.
- You can make several pieces of armor or clothing to do almost anything you want (besides strengthen your enchanting).
- With the Extra Effect perk, you have several options when you're enchanting your equipment, making them much stronger.
- You can sell enchanted items for a lot of money. (Sneak and Carry Weight are the most expensive ones I know of).
- A few examples of costumes you can make is for stealth, pickpocketing, lockpicking, carrying weight, buying/selling items, unlimited magic of any school, and more!

Cons:
- You have to find or buy your soul gems and then fill them to make your item.
- Enchanted weapons require a lot of soul gems to use the enchantment.
- Filled Grand Soul Gems, one way or another, are difficult to obtain.

This is what the build would look like if you're trying to access everything and spend the least amount of perks as possible.

It's fairly reasonable.

http://skyrimcalculator.com/#187973

If I were doing this, I would do it a bit differently.

First, I would skip the cost reducing spell perks and use enchant to make the cost of the spells I wanted to use reasonable. Other than alteration, none of the cost reducing perks beyond novice are needed to unlock another perk. That would give you another 17 perks to distribute elsewhere.

If you want to use illusion effectively at higher levels, you need Aspect of Terror, Hypnotic Gaze, Rage and Dual Casting, otherwise the enemies will outlevel your spells. I'd also pick up masters of the mind. That's five of the 17 I'd save by not doing cost reducing perks.

I'd skip destruction dual casting and impact and pick up the damage buffs for fire, frost, and/or lightning instead. That's another six perks of the 17. So I still have six left to redistribute.

In conjuration, I'd go up the necromancy side instead of the summoning side to get twin souls. It is fewer perks and the perks on the necromancy side are more useful IMO, plus, elemental potency breaks summoning staves, so I never take that perk. So, I have gained a perk in congeration, which gives me 7 left to redistribute.

I'd pick up respite in restoration. Now I am down to 6 again.

I'd skip the magic resistance in Alteration, since you should be able to get enough magic/elemental magic resistance from potions with those 7 perks in alchemy. In fact, I'd probably skip alteration altogether, since you will be wearing armor. So I pick up another 8 perks,and I am back up to 14 to redistribute.

I also think you underestimate the usefulness of the slow time archery perks and the perk that lets you move faster with a drawn bow. You can do just fine as a non-sneak archer long before you get quick draw. I am not that big of a fan of quick draw but I'd at least put two into steady hand, and maybe three more to get Ranger. So, now I am down to 9 perks left to redistribute.

In Block, I'd switch power bash for the slow time perk since power bash does not really do much damage (better off using you stamina for a power attack) and the slow time perk can save your bacon.

In light and heavy armor, I would not take the perks for wearing all of one kind of armor, nor would I take as many perks for the plus 20%. So, lets say I save a total of five perks there, that would give me 14 perks to redistribute, more than enough to put some perks into all the way to dragon on either heavy or light side and then you would not need as many perks in your armor skills to hit the cap. I will take the heavy side for better weapon damage, plus arcane for a total of 7 perks, leaving me with 7 perks to redistribute. I'd take wieghtless inheavy an light armor plus the windwalker in light armor so my stamina regen rate was increased. Either that or Extra Pockets, poisoned and weightless armor in only one type of armor.

If I was trying to make an all around do everything character I might do it more like that.

EDIT: However, I much prefer to have a bunch of highly specialized characters than a jack of all trades.