Ok so I am going to start with a dark elf which I have never done before. Below is obviously their starting skills.

+10 Destruction,
+5 Alchemy, Alteration, Illusion, Light Armour, Sneak

Should I focus my perks primarily into these perk trees or branch out a different route? Im basically looking for a Mage/Warrior/Assassin guy.....Perhaps Im being to broad. Any thoughts or advice. Or maybe a better playstyle for a dark elf?

P.S Quick note on destruction - Is it worth concentrating one either fire, frost or shock or all of them?

Ideally looking for a good build that works with the dark elf, as I am not sure how to invest points wisely..

I made a similar character. She was pure destruction based mage in light armor using sneak and illusion.

I used fire as my main choice of attack.
I could be wrong but I found frost magic may have been more stealthy when firing from sneak. I also used to place destruction traps for the enemy to walk into.

If you're going to use Destruction and Sneak, then Illusion is your friend. Pick Silent Casting perk in Illusion perk tree.
My suggestion is this :
- Destruction
- Sneak
- Illusion
- One-Handed
- Light Armor

Hope it's helps.