Gather from the safe side
Herbalism supplies Alchemy. Swiftness Potion creates distance, Free Action Potion prevents new stuns and movement-impairing effects for 30 seconds, and Major Healing Potion gives recovery outside the global cooldown. Gathered herbs keep those tools available on the route.
Useful herbs
Potion inputs from Peacebloom and Silverleaf at level 1 through Stranglekelp and Bruiseweed around 15, then Goldthorn and Kingsblood in the 30s. The herb curve follows the potion curve.
Black Lotus at 55+ remains valuable on a fresh server. Mid-tier herbs also sell to players who do not gather their own.
Gather nodes on a cleared path. Leave nodes that require a detour through uncertain terrain.
Read the terrain
Classic puts herbs near cave mouths, cliff edges, elite packs, and respawn-heavy patrol lanes. Goldthorn behind a Venture Co. patrol in Stranglethorn is a bad route. Take the node on your path and leave the one that closes the exit.
Best fits
Druid gets Ashenvale, Stranglethorn, and Feralas density on an existing path. Hunter sees strong Barrens and Stonetalon coverage, and Shaman shares the Horde-side lanes. Mage and Warlock spend more time in humanoid-heavy zones where the herb supply is thinner. Choose the profession that fits the route.
Leave the risky node
Leave the herb when reaching it costs a risky pull or removes the exit. Another node will appear.