Wow! Food photography is tough! To break into professional photography you have to know how to photograph food so that you can satisfy your clients and you need a portfolio of exceptional images which illustrate your ability. Then you need to identify prospective clients and begin hustling for work. A mailer with an incredible image, or several incredible images, is a good start. Follow up with a phone call or email . If possible, you want to get in front of your prospective clients and develop a relationship. You have to convince these people that they can trust you to produce the images they want consistently. Remember; you are a photographer 20% of the time and a marketing person 80% of the time. Good luck!