As part of my own interest and my undergraduate degree, I was required to take classes in photography. One of the classes was 'Photojournalism', and one of the assignments was to take photographs of unsuspecting people.
Some people can get away with this unnoticed, but I always got noticed. I've never been able to 'blend' into a crowd. At work, at school, everywhere - I just seem to get noticed. Perhaps it is because I had no style sense or I am tall; I am just shy of 5'9". Perhaps I have an aurora or energy around me. For someone who has always been shy, being noticed was a problem for me. Anyway, needless to say, I never had many decent photographs in these assignments for 'Photojournalism.' I was envious of the photographs that some of the others had managed to take, and I have always been envious of their ability to 'blend in' without being noticed.
I came across an article about street photographer Garry Winogrand (1). According to the article, his technique was simply to take photographs as he was walking down the street, and he usually went unnoticed. As a result of these techniques, several examples of beautiful photographs of ordinary street scenes and people were documented.
Perhaps it is a case of 'practice makes perfect' and not drawing attention to oneself.
(1) Riggs, Ronson. Taking Pictures of Strangers, Part II: Garry Winogrand. http://www.mentalfloss.com/blogs/archives/12903 [March 5, 2008].