The power of shape - Silhouette

Shape is an amazing element when it comes to photography, next to light I think it's the most important part of a photograph (disagree with me, comments). When you remove texture, color and form you are left with a silhouette. So why would you try to remove texture color or form from anything, I think when we do this we allow the mind to see the item and "fill in the details our self" so we also need to provide enough information to help allow the viewer to fill in the details.

One of the "Rules" of photography is always have the sun at your back.  I say try a few shots with the sun behind your subject, try it, think about it when you are outside taking photos.  To get the best shot take your light reading on part of the background that you want correctly exposed, if you miss this part you might have a poorly exposed silhouette.

Here are two examples of silhouettes that allow you to fill in the details:

For this shot I took my reading off the sky (the beautiful blue sky).

For this shot I used the letters on the glass divider (it's not exactly the background like I mentioned above but the background is very boring). 

Check out this book: Adobe Photoshop CS5 for Photographers: a professional image editor's guide to the creative use of Photoshop for the Macintosh and PC