Below you can find profession leveling guides for every profession in World of Warcraft. These guides are up to date with the latest 9.1 patch.
Shadowlands Guides
Fishing
ArchaeologyClassic Guides
The Classic WoW and TBC Classic guides are on separate pages. You can find them here:
Classic World of Warcraft Guides Burning Crusade Classic Guides
Guides for Past Expansions
Professions skills are split between expansions now in retail WoW, there is a separate skill bar for each. You will find guides below for each World of Warcraft expansion.
Alchemy
Blacksmithing
Enchanting
Engineering
Inscription
Jewelcrafting
Leatherworking
Tailoring
Herbalism
Mining
Skinning
Cooking
Fishing
Fishing & Cooking