One way to instantly improve your images is by using the "Rule of Thirds". Mentally divide your image frame into three horizontal and three vertical grids You will end up with two horizontal lines and two vertical lines. These lines can help you create a stronger composition by placing vertical and horizontal planes along the imaginary one third lines and by placing the subject at the intersections of the horizontal and vertical lines.This will keep you from splitting your images in half, either left to right or top to bottom. It will also help prevent you from "centering" every image.
Remember the Rule of Thirds the next time you are taking a photograph and perhaps centering isn't the best composition. Sometimes you can make a stronger image with a small swing of the camera.