Ensuring payment when selling on marketplace

I'm moving to the countryside and have to store my stuff in a trunk room for a few months, so selling stuff to avoid mold risk. FB marketplace has always been shady to me and i've never sold anything on it. I'm only accepting cash payments but I don't know how to sus out if something is counterfeit or not (is this a big risk with marketplace?). Most of the "interested" offers I get are from people who seem to be from the same country/set of countries with empty profiles usually listing cars for sale….

What are the biggest risks here as a seller? Is cash on meetup/loading generally the best way, and how do you spot fake money?

EDIT: Yes, am also using Jimoty

by cuatrofluoride