Finding models is the question I'm most often asked in workshops and when I show work. And there are many different answers.
Finding the first model is usually different. The above mentioned idea of a workshop is a good one. Most good workshops will have a number of models to shoot. That builds up your portfolio quickly as long as they don't all look as though they were shot in the same place.
I believe, the best place to look for your first model is at home and/or you're circle of friends. My first model was my girlfriend at that time. There most likely is nobody who trusts you more on the planet. Trust between the photographer and model is very important to the work, even more so in the beginning when you're not sure what you want to do.
Also if you have taken life-drawing classes in school, they have models but they also have classmates who are comfortable with figure work and they know you.