This may be the best one on this list:
"1. Be reliable. Craigslist buyers are notoriously inconsistent. If you return emails/calls when you say you will and show up at the appointed place and time, congratulations: You are already in better shape than your competition."
Please please please just show up when you say you will. It's insanely frustrating taking time out of your life to sell something and the buyer not show up or call or email.