Are you doing roulettes as well for your items? The way I make a decent chunk of my Gil is from doing dailies.

Roll on everything. And I mean every piece of loot. Turn them in for GC seals and buy some Cordials or mats that sell well on your server. Maybe buy some ventures and get the sweet random junk or treasure from you retainer. If you have a battle class retainer try getting some Dragon Skins or Chimera Manes, unless they sell for dirt on your server ofc.