Herbalism is a must, and your choice really depends on the amount of gold you have on you. If you already have enough for your mount and about 500G extra, choose herbalism/Alchemy and power-level Alchemy (At L32, you will be capped at 225 skill) by buying mats at the AH.
If you aren't rich, then herbalism/skinning is probably better, since mats always sell well.
As far as levelling those gathering skills goes, you are going to have to spend a lot of time in areas where the mobs won't give you any XP to get those skills up to a point where you can gather in your normal questing areas. Sorry, but that's a necessary evil.