Attend local film festivals. In addition to major festivals such as Cannes and Sundance, most cities operate a weeklong festival. Consider going to student film festivals at graduate film programs.
Consider purchasing a feature film that you have screened at a festival and believe has mainstream appeal. Be patient to find the movie that grabs your attention and will interest a large viewing public.
Take the purchased film to a larger film festival, if possible. As the film's new producer, you might get interest from studio executives or other investors and be able to sell it for a profit immediately.
Arrange a private screening with film critics or studio executives. If a prominent film critic gets behind your movie, his support can help you get the attention of executives. This will require contacts in the film industry, but you will be able to build contacts after a few years investing in films.
Distribute the film yourself. Film distribution can be very difficult since you will need to negotiate with movie theaters individually and promote the film yourself. If you have few contacts, though, this can be a profitable alternative to selling the movie.
Secure a distribution deal with a television network, after your movie's theatrical run is over. Selling the network rights is another way to boost your profits. HBO and Showtime are often interested in movies for adults, while the basic television networks will buy the broadcast rights of family movies.