tedster - 9:06 pm on May 31, 2010 (gmt 0)
Here's a start:
1. Do not make any other major changes at the same time.
2. Retain all the same file paths - this makes a url-by-url 301 redirect rule much simpler, and you're less vulnerable to technical errors that way.
3. Be sure that the new domain avoids canonical URL problems.
4. Use the WebmasterTools "change of address" form.
5. Monitor WebmasterTools obsessively until everything stabilizes.
6. Notify important backlink sites about your address change - give each one the specifics they need to know to change their links quickly, and include a note of appreciation.
Here's a thread from 2007 [webmasterworld.com] for additional reference.