Look at TP indexing sites often to see if anything is flippable.

Maybe I'm just bad at it but I could never make more than a couple g with it, seems pretty inefficienct if you look at the amount of time you put in vs the ROI.

Who knows, I've never understood how to profit from flipping.

Whenever I've needed a big chunk of cash, I make a legendary and sell it. That won't work for everyone but at least at the rate I go through money it sets me up for a long time and makes the effort worth it. Another option for slow and steady progress is flax farming. Park a bunch of alt characters at the circle in Mount Maelstrom with reaper's sickles and then sell vials of linseed oil. For the effort and time it's a good return.