well, to begin with, cooking is a "free" profession, so there really isn't a reason not to do it. basically, it will turn all the random drops into products that sell for slightly more, or are more beneficial than just the regular food and water that you summon.
As for your other two professions, I HIGHLY recommend taking tailoring as a first. the ability to make your own armor with stat bonuses is just to sweet a deal, then throw in being able to make bags and the such, it becomes fairly staple.
the next is a toss up. Skinning can be useful as your tailoring grows, as many of the higher tailoring skills require some leather to complete. If you don't have a freind that can skin, you are SOL unless you want to hit the auction houses.
Enchanting is my prefered second profession, but be warned, it is expensive any way you look at it. you must either lose money due to disenchanting (destroying for magical regents) instead of selling, or from buying magical regents from vendors (i don't recommend this. the prices are outragous, and the quantity is limited.) but, Enchanting is a nice treat for yourself and your guildmates, so talk them into sending some magic items your way, to help you with the strain. This also goes well with tailoring, as you can disenchant a fairly low-level / cheap tailoring item for magic, to help get you through the grind.
As for Herbalism + alchemy professions, i have never done them, but they seem like decent choices.
One option you might want to take a look at is Mining + engineering. If you are a gnome, you have a +15 bonus to engineering as a starting ability, so that can help swing your desicion. both my gnome mage and my friend's undead warlock have this as our profession, and it works out nicely, as engineering makes some very handy, versitile products. and as we know, versatility is good.
Hope this helps you out a bit, but remember to do what you choose. if you don't like your choice, you can always unlearn it and take up a new profession...
it has always been the perogative of the half-wit and the child to point out that the emperor has no clothes. But, the half-wit remains a half-wit, and the emporer remains an emporer.