It essentially breaks down like this:
- Pick up Herbalism from a trainer.
- Get Herbalist's Gloves, enchanted with Advanced Herbalism.
- I recommend installing the Cartographer and Outfitter addons.
- Start in Elwynn Forest and run around, gathering lowbie herbs.
- Elwynn Forest > Trainer: Journeyman > Westfall > Redridge Mountains > Stranglethorn Vale > Trainer: Expert > Stranglethorn Vale > Swamp of Sorrows > Hinterlands > Trainer: Artisan > Hinterlands > Felwood > Azshara > Outland + Trainer: Master
Equip the gloves whenever a herb is within ten levels but still out of reach -- here is where OutfitterFu comes in handy. Follow the herbs on Cartographer (filter in only the ones you are working on), making circuits around each zone, as thoroughly as you can. It takes a long time to raise your skill, but I got exploration achievements for every zone while herb grinding.
Stick with it and you will raise your skill from 1 to 300 in 5-10 hours. It takes longer to fully explore all the zones for achievements -- especially Azshara!
Gaiwyn of Proudmoore