Look through your clip file and take out your favorite three to five pieces. Put yourself in the role of the designer for each piece and visit a few microstock sites to search for images you could use to create a similar project. Take note of the messages you are trying to communicate and the types of images you actually find.
Pick one of the images you found and try to shoot a similar concept (don't just copy what you see; make it your own) that could be used in the same way. Don't focus on the technical quality of your final photo—just focus on the process.