All of these pictures illustrate the rule of thirds - for the most pleasing picture, position the main subject (in this case the eyes) where the lines dividing the image into horizontal and vertical thirds intersect.  The 3 on the left also violate one of the rules of composition (as defined by bird photographer Arthur Morris) - leave room for the subject to move into the frame.  The scrub jay, below, doesn't violate this rule, but only because I used PhotoShop's rubber stamp control to enlarge the frame! In this picture of Wolf's Head State Park, Maine, I made use of the trees to either side of the image to help frame it.  The grass blade in the photo above also does this, to an extent. Strong vertical, horizontal, or diagonal elements can enhance an image, as the image below illustrates. This image of a Hummingbird Clearwing Moth illustrates not only the rule of thirds, but another compositional point.  The eye (at least for those of us who grew up reading western texts from left to right) starts at the top left and is drawn right and down.  This may differ in other societies; someone who grew up reading Chinese or the Koran might look at an image differently.  Anyway, this picture does violate one of Art Morris' rules of giving the organism room to move in the frame - but I couldn't crop out the wonderful little thistle bud in the lower left corner.  The eye finds it somewhat later, almost as a surprise. It has been a tradition in biological illustration to draw or render lateral views of animals with the head to the left, thus showing the left side of the animal.  This isn't so much a rule of composition as a convention.  Which of these images strikes you as "normal"?   Anax junius on a cool morning.  The abdomen, which is normally bright blue, is purple and will turn blue as the insect warms up.  The thorax will become a bright green.