Looking through PictureCorrect.com's Top 10 Photography Articles of 2011 (is it top 10 time already?!), I found the one on Street Photography to be especially interesting.
The first tip that caught me was this one:
You’ll be headed out to a tourist spot, so dress like a tourist. I’m not kidding. Although you may have lived in your city for 50 years, get yourself a tourist map and dress like you have just arrived from the mid-west on vacation. I’ll leave that part for you to figure out.
Visit a crowded tourist attraction where everyone has a camera. Dress and act as just another tourist. Study your tourist map. Gawk at the landmark like everyone else. And keep an eye out for interesting subjects.
And why do you want to look like a tourist? So you can do this:
Start off like everyone else. Take pictures of the landmark. Keeping the camera to your eye you can now scan through the crowd for something interesting. As you take pictures, do not remove the camera from your eye even after you have the shot you wanted. Continue to move the camera around pretending to take pictures. Never give away the fact that you’ve taken someone’s picture by removing the camera from your eye after taking the shot.
You may not find anyone worth shooting, but this is an easy way to get started. It shouldn’t be very scary, and you will find that even while standing very close to your subjects you can take their pictures without arousing suspicion. You can employ the same techniques at street fairs, or parades. Just about any crowded area which is filled with tourists is a good place to practice.
The article goes on from there, giving even more useful tips. But that one alone, is both brilliant and simple enough to work.
Time to hit the National Mall, and see if I can't put this, and other tips, to use.