Female Models
Finding good female models can be the single biggest problem for photographers wanting to start boudoir photography. I am still asked all the time where I find these beautiful girls who are prepared to pose for my camera wearing nothing more than a smile. The answer is simple: almost all of my models are professionals, found through one of the many modeling portfolio sites on the web.
There are of course other options: wives, girlfriends, friends and relatives would be the obvious choice. I also know photographers who have some success approaching total strangers... But you really need a portfolio of pictures that demonstrate your abilities, so there is a chicken and egg problem when you are starting out.
Which brings us back to professional models. An experienced model will probably charge around $50/hour, but it is money well spent: a good model knows how they look best and they can flow effortlessly from one pose to the next - so in that one hour you are likely to get ten times the number of good shots that you could with an amateur.
Booking and Working With Female Models
A Model's Posing Guide
List of Model Directories