Use a method of payment YOU are comfortable with, I like dealing with cash, if you arent comfortable then set the appointment at the police station/have friends with you, if its a check or money order, whatever then lets do it at my bank and you can come inside with me, cash in hand if they want to test ride it - but getting on the bike and riding it for them running though the gears is a good show of the bike. Ebay charges a fee, facebook is free, craigslist is $5, BAT charges from $100 and up, not sure what mecum charges if you are considering auction route outside of ebay.
If it's an out of state buyer then I'm waiting for funds to clear my account before the motorcycle ships. The best way to ease a buyers mind are really good pictures of every inch of the bike and close ups, underneath, under the pipes, the oil pan the electrical component condition...the stuff I would have to get on my hands and knees for, and very good video including a riding video, get someone to record you or use a tripod. Don't leave anything up to their imagination and provide before and after pictures. - get on the phone with them while they review the video.....i've seen some people make a facetime call and show the bike that way.
I'm trying to move a cb500 k0 and a cb550 resto mod right now..the bikes are both about ready to send off.
Good luck.