I don't know how you CANNOT have photos these days. It is very hard to get paying customer's attention. It's a minimum.
As to the type of photo, well i don't have a real preferance. Ideally something that gives you an honest presentation of how you look, all while trying to creating some kind of enticement...
I can think of one provider in particular at a massage parlour whom after meeting in a presentation i kinda thought, ''nah,wont see her''. But she later came out with such an sexy pict of herself, i could not get the pict out of my mind and i ended up seeing her, and then repeating about 10 times
....it all started with a truthful yet particurlary sexy pict.