One of the aspects of photography that I enjoy exploring is the concept of "negative space". This is the space that exists between the subject(s) of your photograph. Often times we're so concerned with filling our shots with all the details of a scene that we may overlook some of the empty space that exists around our subjects.
Take this shot for example:
The balloons are the main focus, but the empty blue sky is the perfect backdrop. The photo would be less effective if a tree, building or even clouds were behind the balloons.
This is a particularly good time of year to capture some of these types of photos, well, when we have a clear night anyway. Here's an example of the moon sitting high over a stand of trees. The trees are silhouetted against a darkening sky. The empty space between the trees and the moon imparts a bit of a lonely feeling to the photo:
And of course you can do the same type of setup with the ever present mountains surrounding the Snoqualmie Valley:

A few wispy white clouds are visible in the photo above which lends some texture to the photo, it would also look nice with a pure blue sky.
Designers often use these types of photos for greeting cards, posters and advertisements. The negative or empty space is a perfect place to insert some text as I've done with the balloon photo for my company's New Year's card:
And the same theory can be applied to a portrait:
The black space between my face and the candle really gives the photo the desired depth and mystery.
And here's one where the space around the subject (my daughter) focuses all your attention to the face of the portrait:

So next time you are snapping some photos, take a moment to look around the main subject. Notice what may be cluttering the shot and see if you can take the photo from another angle to leave some negative space around the subject. I think you'll be pleased with the results!
Happy photo hunting and Happy New Year!