The last direction light can come from is behind your subject. This can create some fun and exciting effects in your images. Most silhouettes take advantage of backlighting. In the shot accompanying this post I manually set the exposure to place the sun as a medium orange, this renders my subject as a silhouette. When setting up a shot like this you will be very surprised by how fast the sun actually moves through the frame. It is much easier to frame the subject a little ahead of the sun and let the sun move into your composition. Another great tip is to use live view to frame things up so you are not looking through your viewfinder at the very bright sun. Thanks to Glenn Nagel for that last tip!