I normally do not give money to beggars, especially those who are young and looked abled. As for older men, do not give them as well as many would spent it on beer, alcohol or gambling.
Only recently did I gave an old lady who stood at a starwell near to a coffee shop. Had initially politely decline to give her any money but decide otherwise on the way back to my car. The fact that she did not go around tables at the coffee shop showed that she is not a hardcore/seasoned beggar. She must have been one who needed some money but was too ashamed to openly asked for it in the coffeeshop. I had felt that it took a lot of courage for her to beg for money and felt that $2 was not a lot for me to part with though my wallet was low on cash then.