Ok, I see a lot of people around intermediate or beginning level with this problem, myself being one.
I recommend joining a group or club in your area, or find something around in your area that you can share with others. As Mike said, you need to have something to talk about. You don't randomly go up to people in your home country and use them for talking practice, so don't expect it to be too normal in Japan.
Community centers, local clubs, get togethers, international organizations in the neighborhood... things like this are spots where you can meet new people and share interests.