Below you can find profession leveling guides for every profession in World of Warcraft. These guides are up to date with the latest 9.2 patch.
The Classic WoW and TBC Classic guides are on separate pages. You can find them here:
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.
Fishing & Cooking