Selling a car… how do I have to deal with it?

Hello everybody, it’s relatively late so I’m about to get to the point: I advertised my car on mobile.de at the beginning of the month and two days ago a man called and said that he would be very interested in the car; after a short price negotiation the agreed to my price, told me that cash will pay and that the car could pick up only in the middle of next week. He comes with red plates, said that I can get info about him through internet and actually this person exists, I have a fixed network and mobile number of him, he also told me that has a sale rate of 200 cars per year, I have now deleted my inserat of mobile… What do you think? And how should I deal with the money transfer? I thank you already in advance for all advice that will come… Megadave74