Dan Ariely enlisted a student to help him test what methods are most successful. They discovered standing up and engaging strangers with eye contact worked the best; then a pro showed them the ropes:
There was another beggar on the street – a professional beggar – who approached young Daniel and said, “Look kid, you don’t know what you’re doing. Let me teach you.” And so he did. This beggar took our concept of effort and human contact to the next level, walking right up to people and offering his hand up for them to shake. With this dramatic gesture, people had a very hard time refusing him or pretending that they did not seen him. Apparently, the social forces of a handshake are simply too strong and too deeply engrained to resist – and many people gave in and shook his hand. Of course, once they shook his hand, they would also look him in the eyes; the beggar succeeded at breaking the social barrier and was able to get many people to give him money.
The Dish 