Photo walks with groups of people are great when you're starting out, especially if you're going out into town centres at night. It really does boost your confidence and that improves your creativity. You also get more cooperation from the public rather than grief, as a lot of people want to have their photo taken (this can cut down on the opportunity for candids, but they're still there).
Here's a couple from the recent Worldwide Photo Walk, including some I wouldn't have otherwise got:
Taking photos of the homeless or tramps is as easy as you want to make it. Have a pocket filled with some £1 coins, take your photo and drop a coin or two into the guy's or girl's hat. Talk to them and ask themhow they are. They are human like anyone else. Most enjoy a chat and can be quite intellectual an philosophical. See here: http://www.flickr.com/photos/amazons...n/photostream/