Rule of Thirds: When you take a photo you don't want to have the subject straight in the middle of the photo, so for a rule split the photo into thirds and have the subject on one of the third lines.
Focus: Make sure that the subject is in focus, and anything you dan't want to be a subject is in less focus or non at all.
Fill the photograph: Make sure that the frame is filled and not too empty.
Know what you are taking a picture of: Make sure you why you are taking that photo and what is interesting about it.
Use Depth: Don't take flat images, use the background and space to give depth to the photo.