Cash, cash, cash.
Make sure you are not on your own.
When purchaser wants a test drive, accompany them, check his / her licence and if your insurance doesn't cover them to drive, check that they have their own.
Get purchaser's name, address and signature on registration document and post it to Shannon, don't hand it over. Get purchaser to sign a bill of sale stating they are buying car "as seen", don't volunteer any information, but do answer questions honestly.
Take your insurance disc off the window before handing over the keys.