lol just realized i never visited anywone in like over 10 hours playtrought lmao didnt even no you could thanks
protip you can also have practice sex with them in the same menu to increase their stats separate from the prostitute work menu and it's more VP efficient than using prostitute work since visits have a lower VP drain. Visiting them individually will also increase affection whereas Prostitute Work doesn't which is helpful if you are grinding out lover status, not to mention it's basically like adding 6 additional slots to your prostitute work page.
Masturbate > Increases Foreplay/Sensitivity
Pleasure > Increases Sex/Sensitivity
Service > Increases Foreplay
Sex > Increases Sex
I also suggest not improving the brothel too much for customer service quality, and advertising until you have a bunch of solid ranked prostitutes because then you'll be stuck with very picky clients. There is no actual negative penalty to the brothel but it will make raising money harder because all the low ranked prostitutes will barely earn any ein. I think the "Better reception" expansion also can cause problems with that as well but I can't recall atm.