Mining serves three professions: Blacksmithing, Engineering and Jewelcrafting, so it's really good combined with any of these.
Learning Northrend Mining
You can learn Northrend Mining from one of the NPCs below:
Both faction can learn it from Jedidiah Handers at Dalaran. (Northrend, not Legion Dalaran)
1 - 75
You can level from 1 to 75 in both of these zones below.