A Paladin tank, for instance, should focus primarily on Engineering for the first profession and the second profession should be Jewelcrafting.
Professions have different level bars depending on the expansion. So, there's less of a way to feel truly lost, but it's best to pick up a couple of professions before getting too into the game. Players should search online or ask a guild member for advice on what profession they should choose for their given class and build. A Paladin tank, for instance, should focus primarily on Engineering for the first profession and the second profession should be Jewelcrafting.