Instructions
Post an advertisement for a professional shoot with free images. There are a number of online classified websites on which individuals can post an advertisement. The risk with this type of casting call is that you have no control over who will show up. You can stipulate in your ad the age and sex of the models you are looking for, but after that you do not know who will answer the ad.
Contact former clients, family and friends. Tell them about your idea for your project or the reason why you need portrait subjects. Suggest to them the type of individual you are looking to photograph. You may even have someone in mind. If so, suggest this person to your friend or family and gauge their response. If the feedback is positive, you can ask your family member or friend to set up an introduction.
Contact former college instructors or other photographers who you may know or have worked with. Tell them the type of portrait subject you want to work with, and see if they have any suggestions for people you can contact.
Contact a local modelling agency. Explain the nature of the project, the type of portrait subject you want and what you are able to offer for compensation. The agency should be able to give you a list of models who can be portrait subjects for you.