Just, please, do not agree to sell to someone, set up a time to meet, then tell them 30 minutes before that the items was sold to someone else and is gone. I had a person do that to me yesterday. She had my phone number and everything. why could she not have called me and said, "hey, I have another person who is interested, willing to pay full price and wants to pick up right now. I agreed to sell to you, so if you can match it, it's yours, otherwise he gets it"
Also, make sure the buyer pays CASH, nothing but CASH. No checks! Way too many scammers out there.
Don't give the buyers too much time. 24 hours or less, then move on to the next one. The serious ones will be responsive.