Below you can find profession leveling guides for every profession in World of Warcraft.
The WoW Classic, TBC, and WotLK guides are on separate pages. You can find them here:
WoW Classic TBC Classic WotLK Classic
Guides for Past Expansions
Professions skills are split between expansions now in retail WoW, with a separate skill bar for each. You will find guides below for each World of Warcraft expansion.
Fishing & Cooking