personally, once I made my first million I started buying up under-priced materials in archeology, scavaging, and bioanalysis. I spend about 1 million credits per day buying up low priced material and then turn around and re-list at going rate which turns into 1.5-3 million credits. Rinse and repeat every day.
I do not bother crafting but rather pick just gathering profession of archeology, scavaging, and bioanalysis on all my toons as those materials sold are 100% profit.