I recently hit 80 enchanting and gave myself (with the help of a weak ench potion) 0 mana destruction spells and my follower +100% magic resistance (even tho it caps at 80%).

The game is now too easy for my tastes. Doing a quest takes 5 minutes and I feel more at risk when riding my horse on a mountain than when I'm fighting multiple giants.
On the other hand, the last boss I fought was Morokei, and it took me maybe 14-20 deaths to finally beat him (@ lvl 12, master difficulty).

Are there any personal rules you follow to make the game more challenging, but still not so difficult as to resort to tactics of "How can I manhandle this bosses' AI?"

Would never take -100% cost, that level of spellcasting power would take all the fun out of the game. My character is unarmoured, however, so anything else is fair game.

On my warrior I do not enchant at all, use potions or alchemy, use healing spells or have any companions and I play on master. Quite often I will have to revisit places because they are too hard to complete the first time. This is how I get my fun.

Yes, there are exploits and skill combos in the game that allow you to create an uber character. What I do to avoid this is not grind on a skill, or choose the Perks, that I know will make me to be overpowered. You really have to go out of your way and grind on things to be over powered in this game. To that end, my current set of Enchanted items was made 30 enchanting levels ago. I could improve them by making new ones, but I choose not to. So, you don't have to make the uber enchanted items, then you won't be over-powered by them.

My L44 character has Enchanting in the 70's. This is a character that only uses Enchanted Weapons, and makes a set of enchantments for every piece of armor they have used. I also recharge my weapons alot. But, I don't grind on the skill.

I'm never quite sure how to respond to those trems. Why would you create that situation for yourself in the first place?

For enchanting is there a "sweet spot" for X/5 perks to put into it?I am still perking til the 2 enchants but would 1/5 be enough or should I shoot for 3/5?

Same for Alchemy.

In Oblivion I remember using the Sigil Stones to make a 30% invisibility ring and then 70% Spell (with magic cost) not too sure about exct percentages but it was 100% invisibility... used it for an entire oblivion gate and man was it boring. So I dropped the ring in the river.

Its not very realistic; as you basically become a god and by character chose not to be invisible all the time, why would anyone do this?

There was a mod to limit such things though.

Sounds like you did something wrong, but I cannot say what it is. One rule I can give you is to use Enchanting when you need it.

My character is grossly overpowered; Enchanting + Blacksmithing + Heavy Amor + 2Handed + Archery + Conjuration. Used Enchanting to make conjuration free so I could dump everything into stamina and health. Used Blacksmithing to hit 610 armor cap with daedric armor. Used racial + enchanting to hit 65% resist magic. Used Enchanting to fortify health and stamina (health 400 stamina 300 at level 40). Weild a 2Handed Daedric Sword that does about 150 damage + 20 health absorb + 35 fire damage. I didn't use synergies to make super overpowered weapons or enchants, but with my build that's hardly necessary even on Master.

The way I play is I enter a dungeon and dead thrall the first couple things that put up a bit of a fight. From there I just sit back and laugh maniacally as my thralls kill their friends, and anything strong enough to defeat them is subsequently killed and thralled as a replacement. Any severe challenges, like Ancient Dragons or Dragon Priests I will fight alongside my thralls if they're struggling.

Building this character was a moderate amount of work and testing and replacing my thralls is just as fun as carving up things myself. It's not all that challenging so now I'm just hyper-focused on enjoying the story, being a bastard and putting my thralls through the most punishing tests I can find for them.

I had never done it before :3

I try not to make my main character overpowered but on my magic character I use every exploit possible and basicly become a god.

Off topic - What does " :3 " mean?
On topic - You had to know what you were doing at the time. I mean it shows you that you are getting 0 cost to cast.

EDIT : An easy fix would be to just take it off.

I don't use enchanting, smithing or alchemy at all.

I hold myself to be true to my nature: basic laziness

Which means I only enchant stuff when/if I have a lot soul gems lying about, need cash and/or really feel the need to upgrade something ....so my enchanting skill goes up rather slowly.

I also generally pick armor just for looks and tend to like the more primitive stuff (fur, etc). It keeps me humble and from getting too overpowered too soon

On my current mage, I set of limit of ONE self-enchantment to fortify any particular magical skill. I can make it 29%, and have another 15% from Archmage robes. So, for the two I chose to do that with, I have a total of 44% reduction. To get more, I have to spend perks on the appropriate skills, which I have done (though only up to expert so far). So, I have a total of 94% reduction for two schools, which cost me 8 perks points total (really 6, since the novice level is required to use ANY perks in a tree, anyway). That, along with the magicka regen from archmage robes and Morokei seems to balance pretty well. I can have a magic fight using Incinerate or Thunderbolt, but I will run out of magicka after a few casts. It come back quickly, but sometimes not quickly enough. It feels pretty balanced.

I don't use the stagger perk, either- in fact, I don't use any of the two handed casting perks. I prefer to get 2x damage for 2x magicka, instead of 2.2x damage for 2.8x magicka.

http://www.internetslang.com/_3A3-meaning-definition.asp

(If you'd ask me, it looks like a testicle face.)

":3"=kitten face, implying "I really didn't know what I was getting into." I figured I was going to get powerful, but not THAT powerful -- some thing you only know once you try out.

And yea, I'm thinking of reloading my character back to before I made the new gear and make just a circlet of destruction.

sounds like a reasonable rule. I can't make -29% myself so maybe I'll use a ring of destruction as well.

The other thing I'm considering just from an RP perspective is duplicating the enchantments I get from quest gear onto more aesthetically pleasing item models, for instance I would like to make the circlet of destruction because Morokei makes my character look like a sociopath .

Ha! That's exactly what I see.

I got ya. I'm too old to pick up on all of the hip little postie faces.

Still, I always keep my Enchanting to 1/5 and just enough to get Fire and Double Enchantments. The same with Alchemy. Just enough to get the Double Lasting Poison and Purity, per my characters RP or build. Taking both to that limit ensures me being able to improve my equipment to Legendary status. There is no need to push it beyond that. Besides, I don't actually think that the game was meant to let you improve weapons and armor past that point to start with.

As far as cost reduction enchantments. I really don't worry with them, as long as I have enough to be effective.

My first character enchanted a dagger with soul trap. I have not enchanted anything with any of my characters since. It seems too overpowered and by not enchanting it makes hunting for loot and shopping at merchants more fun because that is the only way to get enchanted gear for a nonenchanter.

However, my mage has finally come to grips with the fact that he needs to take up enchanting in order to control the magicka inefficiency problem he has discovered with higher level spells. My rule with the mage will be to make a free cast suit that does not make casting entirely free, just to keep things interesting.

I have to give credit to the people here.
I half expected to come in and read posts resembling "If you use enchanting at 100 your a noob / bad kid, and should go back to the kid's table" ( you know, like if I was on a Call of Duty forum.

In all honesty, It depends on the character for me. With my current character though aside from spell reduction enchantments, all bets are off (Its hard out there for a Heavy Armor, Sneaking-Archer Nord)

I either abuse it to the max or don't use it at all. Same with Alchemy/Smithing. I really hate having skills less than 100 or more than 15.

As some may know I never enchant- EVER. I use any `chanted weapons until they`re used up then throw them away or keep them on display for old time`s sake.

It`s my character`s way.

I hold myself to no rules. I find it dumb in TES.

Never use enchanting.... I limit myself to smithing only as they are OP when combined, even on master difficulty.

No strong non-elemental resistance enchantments. And only Enchanter 3/5.
And I usually cap my elemental resistance at 60%, and I only use fire and frost.

Common enchanmets I use are increase carry weight, and fortify magic skill in a value under 10(+ minor magica regen on body armor).