Level your crafters, Level 50 Crafters can make Glamour prisms which make some gil here and there [depending on your own server of course and how populated it may be] Leatherworking is always a high demand Prism.
Retainer Ventures,Dailies and also when selling and crafting watch the Market board and see what you can sell fast/for a lot. Make sure to watch something that seems to be bought a lot [Look at sale history tab]
Those are my tips I'm not the richest but I ain't the poorest either.