What professions are you going with to start?
I start with skinning and mining. I vendor leathers and hides and save mining stuff for when I drop skinning for engineering later
If you want the big bucks I’d suggest gathering skills related to the engineering skill grind, especially if you are on a pvp server.
As my main is going to be a Warlock I’m just going tailoring and disenchanting. Enchanting/Disenchanting is going to make some gold for me as well.
I sold a stack of linen bandages for 3 silver, only 16 silver to go to train my level 12 skills 
I’m gonna go skinning and leather working to make my own gear and sell the extra.