For PvP, I don't think enchancing your pet is a viable option. Pets can't taunt players, so you *know* you're going to be taking the damage yourself.
There are basically two ways to go - ranged focus, and melee/trap focus. Ranged focus more depends on getting the drop on your opponent, since if a rogue sneaks up on you, you aren't going to be able to shoot him. I could be waay off here, since I've never read any hunter forums, but I think you'll be better off with a melee build to handle the melee classes. You should be able to handle most ranged classes from a distance regardless.
If you do go marksmanship, wing clip is going to become your best friend.
____________________________
Only the exceptions can be exceptional.