Do I put all my attributes in magicka and which perks are useful for Illusion and Destruction, I plan to be somewhat decent in sneak as well, but will probably only use the first perk and put like 3 into it.

Also what's ur favorite tree for Destruction, I think I might go for cold magic, I really like that ice spike spell lol.

From what I recall the right and middle branches for Illusion is most important, at least for me. Gives acess to affecting higher level enemies than the base level of the spell.

There is a glitch with the illusion perk 'Aspect of Terror', which adds damage to fire spells, due to the fire branch having a fear effect perk. If this isn't patched out, it makes fire and illusion the best combination. As for useful perks, all the illusion perks make sense, and some are required at higher levels or the spells cease to have an effect. It's only 13 perks, so I would take all of them.
For destruction, be warned that dual casting is counter-productive, 280% magicka for 220% damage, and is only useful if you take impact. Impact can be overpowered, as you can stun lock an enemy, but it makes up for the high magicka cost/low damage of the higher level spells.

Hmmm... my guess for lvl 50
Stamina: 150 - 200 (to be mobile)
Health: 350 (to be save... damn you enemie killcam)
Magic: 250 - 300

You go sneaky? - Illusion got a perk for quiet casting.
Fire, Ice, Shock? - All of them, Fire for undead / animals, Shock for caster, Ice for the rest (keep in mind: Nord= ice resist, Dunmer= fire resist)

Stun lock is only overpowered against a single enemy. Dual casting is fine with the right gear. All that is needed is some nice destruction gear and magicka isn't an issue any more. Early on yes it can be a problem but later dual casting is the best way to go to maximize damage output.

If you want to influence the minds of high level opponents, you need the illusion dual casting perk (which doubles the level of opponents effected) and the other perks that increase the level of people and animals affected by illusion. A dual cast expert level illusion spell will affect higher level enemies than a master level illusion spell.

Put all your points in Magicka and enchant your clothes for health bonuses.

For as long as you're dressed in clothes, you get the Invisibility spell and the Quiet Casting perk, you don't need to invest in any perks of the Sneak skill.

If you're going to drop one of those damage lines, I'd drop frost because many bandits are nords, undead have frost resistance, frost trolls have frost resistance, and half of all dragons have frost resistance.

Thanks for all the answers but are the attributes correct mentioned above, I though u needed like 800 magicka for some spells

spell cost = base cost * skill multiplier * perk multiplier * equipment multiplier * dual cast multiplier
skill multiplier = 1 - (skill/400)0.65

The cost for spells listed for spells on UESP and the like are just the base costs.

I would certainly agree with the Unconnected one : take mostly magicka, and use fortify health enchants, it's getting tougher, the mages' way.

I need fire resistance, life enchantments, destruction magicka costs and magicka regeration enchantments, and maybe stamina and health regeneration because vampires get crappy regn during day time, that's alot of stuff

You only need all this stuff at higher levels, the lower level spells are weaker, but more efficient in terms of cost/damage. Flames and Firebolt, the weakest flame spells, give the best return for your magicka. It's at higher levels, with the adept and expert spells, that reduction becomes necessary.

So I should be okay for the beginning but later on ur saying that I'm screwed, I'll probably try to get illusion to like 75ish and Destruction to 100 but my char level might only be like 40-50

Not necessarily screwed. You get some people saying destruction is too weak, then others saying the whole game is too easy, so it's a bit of a matter of opinion. At level 60, I use about 40% destruction cost reduction, and a lot of fortify destruction potions, never have a problem on expert, and destruction is a minor skill for me, not fully perked. You may or may not find differently. It's just generally accepted that destruction alone isn't great, but use other schools with it, you should be grand.

Well what attack do u use other than destruction, makes me kinda want to switch to 1 handed heavy armor destruction mage

I have played both a pure mage and a nightblade mage who relies on magic to remain hidden, conjure creatures and mess with people's minds. IMO, the nightblade is a far funner playstyle in Skyrim. But if you are going Destruction mage route than some cost reducing encant gear can be of great benefit.

I do use some one handed, but not fully perked, only the first bonus damage and some fancy moves, but my build relies on restoration and alchemy. Healing spells and fortify health (enchantments and potions) are what keep my unarmoured character alive, along with un-perked alteration. I have the one handed and destruction because you have to be able to do some damage, but I do things oddly, and concentrate on magic to stop them killing me. If I need to kill someone, a fortify destruction potion ups the damage nicely, makes those fire spells really hurt. Also, the Draugr aren't a problem, as restoration deals with them.

My current character is dual wield and I find myself often only using one weapon most of the time which I fear I will do with the next one, unless I put spells on right and my sword on left then I probably will use the destruction more since I want more of a mage character, I just don't want him to be really [censored], I've never made a mage character in any TES game