if you don't want the person to know where you live, simply meet at some neutral location like the walmart parking lot or corner gas station. Actually, this is probably a good idea anyway because do you really want some random person around your home and family?
but basicly, do what flatstick says about the mechanic. if you've taken it to yours and you want to show your honesty, go ahead and bring your mechnics reviews and estimates for any unfinished repair costs. this shows your honesty.
and in the end it's your choice who to sell the car to. if you don't feel comfortable with the person looking to buy your car, you don't have to sell it. when selling my dad's car a few years ago, a guy came by that got out of his car, walked around our car once, and then offered to pay above full kbb price for it by check. guy was a bit shady and we weren't quite sure if he was trying to get off with the car using a fake check. we just said we'd promised to hold the car for a friends daughter until she could come to look at and that we'd call him if it was still for sale at the end of the day.