Finding images to use that are not restricted by copyright is challenging. Creative Commons is a great alternative.

Creative Commons provides free tools that let authors, scientists, artists, and educators easily mark their creative work with the freedoms they want it to carry. You can use CC to change your copyright terms from "All Rights Reserved" to "Some Rights Reserved."

Flickr.com has a search process that helps you find only Creative Commons licensed images.

Click on the search button on the right side of the home page

Click on Advanced Search, next to the Search Button

Scroll to the bottom of the page

Select the box in front of the "Only search within Creative Commons-licensed content" option

Type in your keywords for your search, like "Rule of Thirds", at the top of the page