well, hunters thrive on ranged attack, dex, and agility for starters, they need range to keep their dps high, so confined or vertical areas can be tricky for them, they can use any element, as long as they can make the arrows, so be sure to stock up
sharp shot, double strafe, and focused shot are useful for any set, and mixing stuff in with those is nice to have if you can use them right. when I leveled my own hunter, I used my pet set a ton, although now that it's at 40 I'm not sure how often I'll continue that. In same cases, where you need to kite stuff, they can work better then the other classes, because of the brute force charm and the skills at their disposal
it's a lot of running around too, so come prepared with some speed buffs if you're farming for a while