Thats right. As a rule of thumb, follow the rule of thirds.
The rule of thirds is where you place your subject in a third of your frame, whether it be a leaf or whatever. If possible, try to have something in the other 2/3 of the frame that leads the viewers eye to the subject, that will add even more to the picture.
The center photo with the red leaves is a perfect example of the use of the rule of thirds (even if it's accidental), the red leaves are on the left third, while they curl around to the middle-almost-bottom thrid.
Since you're using a 5D, you shouldnt' have to pan the camera everytime you want to focus on something thats anywhere but the center, just rotate through the autofocus points or do what i like to do and manually focus most of the time.