One type of photography that I enjoy viewing the most is documentary / street. However, it is also the one that scares me the most to go out and shoot. This year, I'd like to try and change that.

How do people go about approaching those on the street to take pictures of? I'm thinking along the lines of buskers, street musicians, homeless, etc. I'm assuming that for street performers you would give a nominal donation to their bucket - but what is enough to justify hanging around and taking pictures? Does paying a performer imply the right to take pictures of them? How do you approach the homeless?

Thanks for any input folks can give. I'm a naturally shy person so this is a rather difficult subject for me, and most work I have done was in the studio, or with a group that actually hired me to come out with them to shoot.