Infographics are awesome tools for giving a big chunk of info in a small, visually-appealing section. They are made so that you can get the general gist at a glance, and understand a concept, process, or idea with minimal reading. You can check out some sweet inforgraphics here, here, and here.
White Space is Not Your Enemy has great information about images and infographics in chapters 10 and 11. I'll try not to restate them and instead share some additional information.
The biggest mistakes I see on the web regarding images are:
- Theft of images
- Throwing all the bells and whistles of whatever program used into the image
- Using too low quality images, or too small of images (or blowing up a small image huge resulting in severe pixelation)
- Promoting Instagram'd, Picnik'd, etc. images like they're awesome professional stuff
- Images that have nothing to do with content
- Including non-professional snapshot-type images just because they pertain to your text