Choosing my duoFollow

In the end I went alch/herb just because I liked the various buffs I got from potions. I looked at the mail pieces that I could make with both blacksmithing and leatherworking and wasn't that impressed. Yes there are a few nice epic pieces that some say can hold you until T5 content, but that's a ton of work to get some of those rare drops from skinning. Plus in the end as you're leveling, it's easy to get new gear from quests/instances especially once you hit outlands.

I'm sure that many people will recommend doing the old gather/gather profession until you hit 40 then pick one gathering profession that you've leveled and work on a crafting that works for your gathering. Plus the money is nice that you can make skinning/herbing and just dumping mats on the AH.

Keep Enchanting; you'll find it useful while levelling and it's currently one of the few professions that will give you useful things in the endgame, i.e. ring enchants.

It's probably wise to match it to a gathering profession such as skinning, herbing or mining as your other profession, unless you are willing to learn how to disenchant things you buy on the auction house for cash--huge moneymaker there--or don't mind being broke much of the time. If you really want a crafting profession, I recommend Engineering because of the many entertaining and useful items you can make while levelling, particularly guns, scopes and ammo for your hunter, plus the power of the goggles and the profitablility of the zapthrottle in endgame.