My mage is currently at level 45. I play on Expert.
I decided to play Breton because I figured I wanted to get good magic regeneration while my Magicka was low, and so I thought I would use the Apprentice stone, and use the Breton Dragon Blood ability to offset the disadvantage. I also thought the High Elf bonuses would become useless at high level, while the Breton ones would scale. But it is not a big deal which race you play. If you play something without good magic skill bonuses, you may find it worthwhile to grind spell-casting at the very start of the game to make up the extra points. Lately I have changed from the Apprentice stone to the Lord stone, because regen is no longer a problem. But it is worth finding ways to increase your regen when your Magicka pool is small.
I have put all my points into Magicka, so currently it is at 540 without gear. This means I can cast what I want, when I need it. I almost never run out. This also means I have to be careful not to be hit. This makes the game much more fun. Last night I fought an Elder Dragon in a small area with little cover, and died maybe four times. At the end of the battle, I saluted him as a worthy foe. To me, this is the fun of RPGs. I don't want to one-shot him and keep on walking.
My skills are currently:
Illusion 100
Conjuration 98
Destruction 92
Restoration 51
Alteration 100
Enchanting 100
Sneak 77
I don't use other skills. I started practicing Alchemy, but have not found a use for it, and if I take it up again I will have to grind it up by 50 points before it is of any use at all. (It is at 27.) I leave all locks unopened, and it doesn't matter at all. I still have 42,000 gold and all the gear and spells I need. Speech is at 47 but there is nothing you can do about that.
Illusion perks: Everything except Illusion Dual Casting and Master of the Mind. I haven't felt the need to get Dual Casting for any school. I don't want to get Master of the Mind, because my tactics would end up being the same for all kinds of enemies. I like it that there are some mobs that Illusion will not work on.
Conjuration perks: The left branch of Atronach perks, and the right branch of spell cost perks. I will get the Twin Souls perk when Conjuration hits 100.I have no use for any bound weapon perks or spells. I am not using zombies for role-play reasons.
Destruction perks: The spell-cost branch, and Rune Master. Just lately I have been getting the perks to power up Shock spells. I have not felt a lack of power in Destruction before now, but getting close to level 50 it is time for an upgrade. So far I just have the two damage-increase perks. Eventually I will get the disintegrate perk, and probably I will get Destruction Dual Casting and Impact after that. This will keep Destruction going up in power up to level 50, when monsters reach maximum level (I believe).
Restoration perks: I don't really use Restoration as I don't get hit (much) and my Health is only 100. So far I only have the Novice and Apprentice spell-cost perks, and the first Recovery perk (which is good to get). I'll get the next Recover perk, and then it won't go up further unless I start turning undead. I will probably do that at some point. I have not found a use for Wards as I try to avoid aggro, and they burn a lot of Magicka.
Alteration perks: I have all the spell-cost perks, the three Mage Armor perks, one perk in Magic Resistance, Atronach for absorbing spells, and Stability which I got once the skill hit 100 as it is counterproductive before then. I will probably get the rest of the Magic Resistance perks at some point. Catching a stray Ice Spike from a distant foe whom I haven't noticed is one way this character tends to bite the dust.
Enchanting perks: I only have the first five perks to make enchantments 100% stronger. This brings things up more or less to the level of loot that you find. This means that there is still some interest in finding treasure, which is one of the points of RPGs. I would prefer to use the other perks on spell skills, and keep loot interesting. But it is useful to have Enchanting just so you can make the specific pieces you might need, and it is also a good money-making skill. Not vital but kind of fun.
Sneak perks: None. I wear gloves and boots of +35% Sneak each, that I made.
Shouts: This character really only uses Become Ethereal, Unrelenting Force and sometimes Whirlwind Sprint for certain situations. You get all these ones very early on if you follow the first couple of bits of the main quest. Become Ethereal is absolutely essential, especially against dragons. If you have a few seconds of invulnerability you can turn the tide of battle. Unrelenting Force is just fun, but can be very useful if you can blow people off walls or hit a few at once.
Playstyle: This character obviously is an indirect fire character. I sneak all the time in dungeons. The idea is to attack from cover and avoid the attention of enemies. This means tactics, which is the fun of the character.
Spell usage, in the order it comes up on my screen. Only the useful ones:
Detect Dead & Detect Life: I think if you use these too much, it can take the fun out of getting jumped, so I only use them in special cases where I am searching for something.
Dragonhide: This is not that much use I suppose, but I forget to use it. You can cast it from within Become Ethereal if you have a tough fight in an enclosed space. Then just drink a Magicka potion.
Ebonyflesh: This is very useful, especially early on.
Magelight: I cast this on my summoned atronachs so that they are a portable light source, and also attract more attention (I hope).
Paralyze: Very, very useful for supporting atronachs, getting out of trouble, and breaking calm spells. Often I paralyze and then cast Wall of Storms over the poor guy.
Pacify: This is good cast from inside Become Ethereal. When you are using it on wild animals, you have to make sure not to cast it as they leap, or they will kill you then become very calm... It is also useful for grinding spells. You can make some poor bear or saber cat your test dummy. Also good when you need a few seconds to plan how you will attack.
Frenzy: This is fun to cast from cover on a room full of enemies or a castle rampart with bandits. Just hit one or two bad guys, keep hiding, and shut the door. Chaos ensues.
Invisibility: This is super useful and I have it up a lot of the time. Good for running through the wilderness and not picking up aggro from distant animals.
Muffle: Not sure how much this hides noise from a character in robes, but it seems to do some good. Possibly useful when Sneak is low, and good for grinding Illusion at low level to get to Invisibility.
Rout: Good for supporting your atronach.
Runes: These are lots of fun at mid level. You cast them silently from cover before you attack. Also, if you get chased, you can cast them in front of you as you run away. Then listen for the "BANG" and cast another one. Various opportunities for creative tactics.
Walls: You can also lay these ahead of time down corridors and such. If you know where a dragon likes to land, you can make him a bed of Wall Spells to sit in.
Other Destruction spells: All pretty obvious.
Atronachs: These are essential. Flame and Storm are for ranged damage, Frost and Dremora are for melee and blocking enemies from getting to you. The first two are useful when you first see a dragon, then the last two are good for keeping him on the ground so you can spam Destruction at him. If you can sneak, go invisible, or go Ethereal, enemies will usually transfer aggro from you to your atronach, which is kind of the point of this character's playstyle. Atronachs sometimes don't cast. Some people say this is due to the absorb magicka effect of the Atronach perk. I am not sure if this is correct. I haven't really tested it. It's rarely a problem, anyway. I've never died because an atronach didn't cast.
Expel Daedra: This is very good to have available.
Soul Trap: This is tricky to cast, but kind of fun because you have to get in close and aim carefully. I cast it when the enemy is pacified, paralyzed or fighting an atronach usually.
Fast Healing: This is the only Restoration spell I really use. Putting it in both hands heals you completely in a couple of seconds.
Anyway, that is how I play my mage and I enjoy it a lot. Every situation calls for different tactics, and you always have a few options. I probably die once or twice per dungeon, but I don't have any battles that are actually frustrating. I know I can beat anything if I think about what's going on.
