I have someone interested in buying my used car. I need to know how to handle the money transaction and car title. Do we need to sign the car title in front of a witness (like a currency exchange) ? Don't I need a copy to show proof that I sold the car? What about the money? Do I make some kind of receipt?

First and above all, all of the paper work should say "as is" "no warranty expressed or implyed" That way a month from now they don't come back for 3000 in repairs on the car.

You want to have a bill of sale, you will sign it, and they will sign it. They get a copy and you get a copy, This is proof you sold them the car, in case they don't register it and have an accident or something.

I would require cash, nothing else, there are fake certified checks, a lot of bad checks. You can meet at their bank or your bank and get all of the paperwork notorised ( all banks have this service)