Just go into your skills and drag out the 'find minerals' and 'find herbs' buttons. Only one can be active at a time, which is why most people take mining/skinning or herb/skinning.
Anyways, Mulgore will have alot of herbs. Ore will be in caves or near mountain walls typically. In the Barrens you'll fin the next step up of each herb/ore.
Anyways, just be sure to turn the 'find xxx' thing on and it'll put a dot on your map whenever you get close to an herb/vein.