Become a Model for Free

First evaluate yourself to see which type of modeling category you fit into.
If you are a female between 5'10" and 6', and your hips are no bigger than 35 inches, you should consider Editorial and Runway modeling.
For men, you must be between 6' and 6'3", with no bigger than a 32 inch waist.
If you are any size or height, then Commercial Print modeling is for you.

First evaluate yourself to see which type of modeling category you fit into.
If you are a female between 5'10" and 6', and your hips are no bigger than 35 inches, you should consider Editorial and Runway modeling.
For men, you must be between 6' and 6'3", with no bigger than a 32 inch waist.
If you are any size or height, then Commercial Print modeling is for you.

To find an agency, go to models.com and upload your pictures onto a free profile. There, you have the opportunity to be scouted by numerous Editorial and Commercial agencies around the world.

Be persistent. If you are not contacted by an agency, search the models.com agency database. 

Find agencies that you feel your look is suitable for (e.g: Editorial, Commercial Print).

If an email address is listed on the agency's profile, email your models.com profile to them (You will be provided with your own link/URL to your profile). If no email address is listed, go to the agency's website, and submit your pictures through their "contact" or "become a model" link.

Many agencies also have "open call" information on their websites (About an hour set aside during one day per week/month when aspiring Models can come down to the agency to show an Agent their pictures/book-portfolio.)