Depends on which image you need. However, use google and type in key words such as:
1. Free coloring pages.
This will give you a variety to choose from
Eg. [url] http://www.coloring.ws/coloring.html[/url
2. (character name) images
Eg. Spongebob Image
Another option of doing it This way is to look above on the google page and selecting IMAGE. This will give you all images.
I hope this helps.