- gathering and sell is the common way
- crafting should give you better but need more investment i guess
- play buy low sell high from market board is also a thing but you really need to stare the market board every minute or so

- the easiest for me is just go duty finder and look whats the "adventurer in need" (mostly tank) and go play as that, it give you instant queue, extra gil, need/greed all the drop and sell them off. its small sum compare to others but since iam not into gathering/crafting, its the only way for me