Stick a point in Sneak, Light Armor, and weapon of choice (one-handed, two-handed, archery) your first three levels (in that order). The 20% boost to those skills is a bigger modifier than subsequent points in the same skill, and help survivability at low levels.
While sneak-archers rock, archery is not a necessity for a sneak character. However, if you go that route, put a point in archery before light armor. Also, take a melee weapon skill (one point) because your archery at first (even with sneak bonus) won't one-hit-kill.
If you don't become a sneak archer, remember that there are many reports that one-handed bonuses don't apply to daggers.
As far as health/stam, I reversed what Holmlund92 says and put my first priority on Health. Stamina is good for two things - carrying capacity and sprinting. You may have to do alot of sprinting at low levels though.

Magicka is optional, and depends upon your playstyle. In my first sneak character, I tried out the Illusion and Alteration trees, so I had to put points both in magicka (to have enough mana to cast spells) and the relevant trees (to reduce casting costs). Keep in mind though that magic-based sneaking is not as good at Sneak-based sneaking - spells have a fixed duration, while avoiding spellcasting and just using the Sneak perk tree will get you silent movement pretty quickly. It's much better to get boots with the Muffle effect rather than casting Muffle al the time.