It's really easy to get archery up to 100 way too early in the game. Now that I have played a few times with the same character, I can do things a little more evenly. Usually the first skill I get to 100 is Alteration. I don't pay for any training except Heavy Armor because I almost never use it unless I happen to be wearing one of those charming masks.And I don't mean through deliberate grinding, like smithing (I deleted that character long ago anyway).
With my current Khajiit Character, my first level 100 skill was, surprise surprise, Sneaking. What's yours?
For my warrior, two-handed. Assassin - I don't remember if it was sneak or pickpocket. I leveled those pretty simultaneously, since when I sneak around people I just can't seem to keep my hands out of pockets.