I like to ride up and down the curbs at my house. Then build up to riding down a few steps at the library or public school. I try to find little obstacles near my house so that when I'm on the single track and come to an obstacle, I'm not as nervous.

The best thing to do, is just try riding it. Go for it. I think you'll find most things are very ridable, you just need to trust your bike to do the work.