Well there are a lot of strategies on the topic but here are a few tips:
On PC: Press the ~ key to bring up the console then enter: player->AddItem "Gold_001"
On Xbox: since there is no console you can always increase your stats with the "soultrap" cheat and then kill and lot of ordernators and then sell their armor to crepper in caldara
None Cheating: There is not a lot of easy ways to gain money until you get pretty high level but here's a few that work
Crepper in caldara has regenerating money so you can sell the more valuable stuff there, I recommend going to aldruhn and steeling the guard towers armor and weapon supplies when the guard downstairs
Or if you could go to vivic and taunt an ordernaitor and jump in the water, he will drown after a while and then you can take his stuff
Also in vivic you can raid the hololu redoran and tevalli treasuries