The best way, not the easiest, would be to go scouting for models. The reason being, is that if you “discovered” that model, when they make it big, that credit kind of falls back on you. They will remember you very well. This is what I call “Virgin Shooting”. Shooting a model who has not ever shot with a professional photographer before. She will talk about you more, as you were her “first”, than a model who has shot with many photographers. Whereas if you shoot with a girl who has been on Model Mayhem ( although there is nothing wrong with that) and has already shot with 30 photographers, you are not making an impact for her nor for yourself. However, keep in mind, a model such as that has more experience and may be easier to shoot with due to the experience of posing.
Model Mayhem is the easiest, but many of them drop off from using the site so you have to spend alot of time sifting though the members to actually find model who are active. And the one who do use it know that there there are quite a few Mayhem Flakers. Flakers are models, photographers, stylist, etc., who talk of the big game of shooting but end up dropping out towards the last minute. That is the great thing about testing with Agency models. If a model flakes on you, it is frowned upon by her agent because it is a very bad habit to have. Agencies, however, don’t just send their models out to whoever wants to shoot. They will decide if the photographers work would be worth the models time. And they also need some type of assurance that the person is legit. If you take a few weeks off work and head to New York for a shooting vacation, you are not going to find an agency to work with you.
If you are looking for an easy way besides Model Mayhem and Craigslist, I don’t think you will find one. Finding models is not an easy task even though it should be. There are many who want to model/have high quality photos taken. Just finding them is the issue. If you can create a great image for yourself and your work (you will need them both) then you should not have trouble eventually your own flow of models.
from Answers by James Santiago on Quora via Quora.