Well, now in WA we have to go through and FFL due to a new law. Don't let this happen to your state!
Back when we were free to do FFLs here was my learning curve.
I used to do a bill of sale, but then decided I didn't really want some stranger having my DL#, home address in writing, or even a copy of my drivers license.
Of course I'm happy to show it to them, but as for a hard copy, I think that's unwise (burglary, ID theft, etc.).
I just keep a PDF copy of their sale ad, email or PM chains, texts, etc, or otherwise just record their phone, full name, city, for my records, and also keep a copy of their emails. These are all sufficient to rebut any allegation contrary to a purchase/sale given there are time stamps which are probably better than a signature which is not notarized or witnessed anyway.
Of course I will ask the key questions on email or text - mainly to ensure they are not a prohibited person, not a felon etc. All recorded neatly in an email. Also creates a record in case you disappear mysteriously.
Good communication in advance to clarify condition, cash sale or trade, expectations, etc. This saves a lot of time, dickering, and weeds out flakes or suspicious buyers.
As for a meet, daylight. Public lot with some traffic but also somewhere that a gun can be inspected without raising attention. A sporting goods or gun store lot is good. Ideally find a camera system to park under in case something goes south. Some will suggest a police station parking lot. Not sure about that one...
I have gone into strangers homes or cars before, but that is not a good practice.
I would avoid that.
I would also never have a stranger over to your home for any transactions.