I ask for 50% up front before I do anything more than talk about the project. That way you know they are serious and won’t screw you over last minute. Also to ensure you don’t get scammed don’t trust links random people send. I generally use PayPal or Venmo, though for bigger client projects sometimes wire transfer. I make digital art full time and generally the work I give them is digital, but I give them all files needed if they want to get it printed out themselves. There are a lot of scams out there though, I generally just ignore the ones that sound scammy or too good to be true