I know someone might have cover this but I haven't find anything that really explain how should a mage play through the early level. I plan to use destruction as main then may be up conjuration later but I'm not sure at what level should I join the College of WinterHold and what should I do if I don't want to jump right into the main quest but able to level up at the same time. It would be nice if I could tell me exactly what skill should I focus on for the first several level and what not. I know that I'm suppose to play the way I see fit but I want a solid char and my way don't seem keep me alive too much... (experienced from recent fail spellsword and pure mage)

Personally I think you need to make a decision as to whether your going to use armor or not and which type. After that it really is down to preference which part of the tree you focus on. However, if you intend to use and perk enchanting in order to create zero mana casting gear, then dont bother with the perks to reduce casting costs as they are then wasted due to zero cost gear.

The College of Winterhold, due to lack of leveled items and the entire game being scaled, is actually one of the best questlines to go into from the very beginning. You will have to fight a few bosses but they're nothing clever thinking can't take care of (especially on adept or lower.)

Also, don't consider yourself only destruction, make use of the other trees as well to compliment your build; all of them fit together pretty well (unless you're being ridiculous and going something like purely restoration and alteration "I WILL TAKE AS MANY HITS AS POSSIBLE AND SURVIVE!")

You just pretend that your sword is a spell and your robes are armor.

Or you pretend your armor are robes, whatever.