Study previous winners. Many photo contests happen on a regular basis and display the previous winners. Study them. Determine what common elements they share, and see if your entries use some of those elements.
6. DON'T OVER-PROCESS
Your entry should stand alone on its originality, composition, perspective and technical expertise with the camera, not Photoshop. You are not going to win a contest because of how deeply saturated the colors are or how adeptly you blurred out the background. Minor editing is usually acceptable, but some contests will disqualify you if you do any, so make sure you read the rules.
You can use these tips and enter the WeSay.com photo contest here.