Herbs are valuable not unlike ore. Usually players go with a combination of Mining/Skinning or Herbalism/Skinning if they are making a character who is a gatherer. Herbalism and mining both require a tracking skill but you can still mine ore and pick herbs if tracking is not on.
Route's to run for Herbs
First we will run down exactly what your Herbalism skill needs to be in order to gather the herbs, then their usual prices in the auction house per stack of 20 and preferred picking locations:

Making maps for routes to run for herbs would be a rather difficult task as herbs spawn locations vary greatly and could waste more of your time than it could help by you possibly chasing down wrong locations. Use the above listed charts and explore these zones in the type of terrain specified for each herb and you are sure to succeed with great speed. If you are looking to raise your Herbalism skill hunt down the herbs in the order they are listed and within the zones listed, soon you will find your herb pouch full and you will be rushing back to the trainer to pick up the next level of Herbalism.