Check the local laws to be certian but in most cases private sale of a firearm is pretty loose. With that said cover you butt, have the buyer sign a bill of sale that includes info off there drivers license (full name, date of birth, address and drivers license number). That way if something happens with that pistol down the road you have proof of when you sold it and to whom. The few pistols I have sold I have required the purchaser to provide a CPL or a CWP and I document the sale as described above. I have purchased a few pistols that the seller wants nothing more than the cash, for those I pay to have the local PD run the serial number so I know that the pistol isn't stolen and I keep a copy of the ad or a note of when and from whom I purchased the firearm from. A easy purchase or sale can come back to bite you if you don't do the due diligence up front and may make it where you are unable to own or buy another firearm in the future.