Well known photographer Eric Kim wrote a book about street photography. To download the ebook (PDF and MS Word formats available) click here and scroll down a little bit. From the introduction:

So why did I decide to write this book? Well one quote that I love is from famous hockey player Wayne Gretsky who said, “You miss 100% of the shots you don’t take”. In street photography, one of the biggest problems that most aspiring street photographers is getting over their initial fear of taking photos of strangers in public (without permission).

To photograph strangers without their permission is strange. Most societies in the world teach that it is wrong to take a photo of a stranger without their permission. In-fact, we are so socialized against doing this that we are worried what repercussions may happen to us if we do so. We are worried that the photos of others we shoot may become belligerent, yell at us, or even call the police on us. Therefore “normal” people don’t take photographs of strangers without their permission—but who ever said that street photographers were “normal” people?

If I could estimate, I have probably shot over 300,000 street photographs in my last five years in the streets. Out of all of these shots, I have only gotten around 3 really negative responses. The first encounter involves an old man grabbing my arm and asking me what I was doing, the second a man in Downtown LA trying to grab my camera from me, and the third being an old Chinese man karate-chopping me in the back of the neck (from a bike) when I took a photograph of him during the night with my flash. Needles to say I am still alive (and in great health) and haven’t ever gotten punched, stabbed, or killed (yet). Also if you do the math, 3 really negative experiences out of 300,000 is only .001%– which is statistically insignificant. You are probably more likely to get run over by a car, die in a plane crash, or win the lottery.