Only buy Fasti and Inka to start. Train them and set them to whoring. The bordello is a shit hole, so no clients will be happy, but you can still make some money. When you are in real need of cash, train your rhetoric in the basilica and start taking clients. A good case can get you 4000 sestertii
I need one last piece of advice, really. The balance between patience and discipline is hard to find. Ignore their reluctance, and they get worse. Beat them too much, and they get worse. I've tried mixing up the sexual and non-sexual requests, but that also seems random.
What is the best way to raise their acceptance? In one playthrough, I've had all three girls fully trained in all aspects, yet their other stats never rise. Doesn't affection for the MC ever develop?