Just Strating out.Follow

I'm just starting in Alchemy too (but I'm 35 heh)

Anyway, from the time playing I have noticed that herbs grow in certain areas, though I'm on the horde side, so I probably can't give you any tips for your lower level areas. However, I noticed that in the newbie areas, you probably won't be able to find anyhting besides peacebloom, silverlead, and earthroot. You'll find more herbs in later zones, like westfall or redridge. You'll start seeing mageroyal and briarthron there.

As for where to find them, the ones off the top of my head:
Earthroot grows on rocks and mountain sides
silverleaf is usually around the bases of trees
Peacebloom can be found in open fields.
Mageroyal can also be found in fields
Briarthorn is around trees and other vegitation
Stranglekelp can be found underwater or even fished.
Bruiseweed you can find on cliffs and in caves,
Kingsblood seems to have any specific condition since I find it in all sorts of places
Liferoot is found on river banks
Gravemoss is found on, you guess it, graves.

Usually you can figure it out just by paying attention to where your finding the stuff, but herbs sort of come in tiers so if you can't find a particular herb, you should try checking out a higher level area.