I sell everything. Of course, it takes an army of mules (limited AH/inventory space), but I gather things into stacks from leveling and sell them.

Since my wife and I have come back the ONLY thing we've done is level jobs from 1-20. Most of them were already there so we've mostly just done a handful from 10-20.

We've literally made 1M gil from selling random crap like sheep/rabbit hides, crystals, seeds, etc.

Since soloing is so easy these days you could easily pick some jobs and level them with nearly no gear and just make some easy money as well as gather beastman seals.