Allure, Confidence, Refinement boost prostitution performance a little bit, but not much.
Endurance has little effect, but it improves courtesans health and energy.
N. services improve moderately.
But after v0.4.0 talents improves the most including building upgrade and improvements.
General skills are great because they're fast to improve which courtesans can get praised for which adds happiness, plus you get extra talent points after every skill level up. So training general skills are great for unlocking talents and praises.
Once the time is right, I'll be adding individual customers to the "end day" event. The lobby will show up and you could pick a working courtesan and set customer/customers for her. Every customer will have preferences for general skills and sexual skills, that way skills will matter more. Night services will be a general skill to boost profits and fetishism for unlocking/training individual sexual skills (oral, vaginal, anal, bondage, group, etc.).