I've noticed that within Skyrim, every level you get makes you stronger. You level your smithing as a warrior and you get better gear, level your block and you get better in general, etc. Following that logic, one would think that the same would apply to a mage-type character. Well I've discovered that by keeping my level as low as possible and only focusing on the necessities in my play-style, I don't have a problem playing on Master with a mage.

To prove this, I started up two characters. One character leveled up every magic skill available to 100, and the second character only worked Destruction, Conjuration, Enchanting, and a little bit of restoration. I found that even though my first character was able to pull off more stunts and surround himself with more defense, my second character could clear any given dungeon faster than my first.

The first character was level ~60 and the second was in the upper 30s.

So what I'm saying is to not become a jack of all trades mage and what you really need to do is focus on specializing. DON'T go into smithing for better gear, either go on the offensive or the defensive and stick with it. Don't try to do both.

Offensive mage example: Destruction/Conjuration/Enchanting/Restoration
Defensive mage example: Conjuration/Alteration/Illusion/Restoration

Just thought I'd throw that out there, as well as the fact that destruction alone won't get you through Master. Work in some conjuration and you won't have much of a problem if you specialize correctly.

Yeah, kinda a no brainer here. If everything contributes to overall leveling, then selecting a few skills to focus on will make those skills more potent at lower levels.

This..

Many of us have been doing this since release, even to the point of not picking up skill books and never leveling speech/crafts.

It is a good find and does make a character
More potent, since you are more concentrated and against lower leveled enemies. Characters become dilluted and the enemies max too quickly if you level all skills broad, also you are a classless jack

My "main" char is always a Jackal

Agreed - specialization allows you to define your character and also keeps things interesting, while leaving some content for your next build.

I do sometimes wish there was some nod to a class system, though. If you could choose which skills contributed to levelling, it would be easier to control the relationship of your power to enemies' power. A lot of skills are possible to avoid using, but it's difficult to avoid levelling Speech, for example.

This is one reason a lament the loss of major and minor skills. You could put your main offensive and defensive skills in major, and your support skills like sneak and alchemy in minors. That way you onley level up by killing stuff, not selling stuff at the a store.