Rule #1 has to do with taking pictures of animals or people who are moving. When your subject is in profile always have more space in front of the subject than in back. Centering the subject creates a very static image. Look at the difference a little change in position makes in terms of added movement for the photos below.
And, if you don't have the composition quite right when you take the picture, you can always crop it to get the right effect.
Cairo, Egypt
Denali National Park, Alaska