show up at their door step with two of your biggest friends and a baseball bat. if he opens door you hit him in the face/chest once and tell him you will kill him if he doesnt pay you right there. if he runs out back then have one friend get the car and the other two chase his fucking ass down and beat the fuck out of him. I did the same thing to a guy who owed me $300, and nobody even had to touch him. He was scared as shit and payed us right there. You must remain confident in yourself the entire time.