1. Homegrown and Public Domain: Use images you create yourself or images in the public domain.
2. Creative Commons: Use images others have granted permission to re-use
3. Fair Use: Use images following fair use guidelines in the country where you live (if available)

1. Wylio
2. CompFight
3. Flickr Creative Commons Image Search (Attribution-only)
4. Other Flickr Creative Commons Images
5. Other Copyright-friendly Image Sources from Joyce Valenza
6. More suggestions on the Images page of TalkWithMedia.com.

Screencast Tutorial