So far, key takeouts are:
- People don't read instructions so make it REALLY obvious
 - There's too much text on most web pages - people skim, they don't read
 - Make use of conventions - they became conventions because they work
 
I'm sure there'll be more!
Reference
Krug, S. (2006), Don't Make Me Think: A Common Sense Approach to Web Useability, 2nd ed, New Riders Press, Berkley, CA