Hello. My son is going to sell his used car on Facebook Marketplace. I haven't sold a used car in 13 years but have bought a few in that time. Any advice on selling in the modern age? Thank you for your time.

When paying by check I would meet him at the bank and make sure funds are there. I always have them sign as and bill of sale with both party's sign and time/date.

You can get a template of those on the internet just print it off.

Cash is king

This. No way to get scammed and you know the buyer is serious if they bring cash.
Money talks, words that the profanity filter will not like walks.

cash or meet at their bank and get the cash there

take good pictures , be honest about what it is and what work was done if any.

meet them not at your house
they are going to have your address when they buy the car but no need to give the entire world your address and have them showing up at your house.

use the Facebook marketplace chat to exchange cell phone numbers and call and actually talk with a human when setting up a meet.

If they bring cash, make sure you know how to identify counterfeit bills.

Shop around and try to find cars for sale that you are selling. Cars aren't just worth what Kelly Blue Book value is anymore. The online carmax and carvana changed things. If you are selling a 2015 Toyota Camry with 75,000 miles then find three of them for sale to know what your asking price should be. Used car market is silly right now.

Junk yards never cared what condition my used car was in.

Make a sort of sale paper stating that the car was sold as is a both parties have a copy stating that with the amount paid.

is that not on the title in MN?

here buyer and seller sign the back of the title and put how much paid because the buyer mails that in to get the title re-issued with their name on it and pay registration and get plates.

both sign you snap a picture of the title I have a thing to make it a pdf and put it in my online drive.
I also ask to see drivers license and snap a picture of that they wouldn't have to provide it but I was buying last time not selling and the guy was functioning as an agent for his father in law who was not there so I wanted to cover my bases even though I had title in hand and car.