Lesson 1: Images capture the eye and attention. They can also take attention away from the intended "on page action" (if there is one).

Lesson 2: Images "forward the story" ~ fill in details. Save a few words with a "real" image.

Lesson 3: Image files need to be optimized for the WWW ~ BIG (high quality) image files . . are reserved for paid downloads.

Lesson 4: Images are often ripped off so a) watermark them; b) digitally mark them; c) include your sites URL; d) consider anti-hotlinking measures.

Lesson 5: Stock images sometimes send the message "cheese vendor", i.e., schlock. Avoid overused images.

Anyone care to share any lessons learned about using images?

I'm particularly interested in lessons learned relevant to blocking image bots. I wouldn't block an image bot (Google, etc.) from "harvesting images" that are "stock" but I'm wrestling blocking bots from higher quality (self generated) images. Don't ask me why. ;) I haven't fully thought this idea through . . but have you? :) :)