If you have to shoot against an extremely light background, over expose the picture a little bit to compensate for it. You will over expose the bright background yet keep the subject in proper lighting. The reverse is true for a light subject with a large dark background. A good practice is to shoot each shot over exposed slightly, exact exposure, and then one slightly under exposed. The advantage of this for the amateur photographer is that if one picture isn't right, you don't have to get everybody together again and repeat the photograph.
Film is cheap compared to peoples time.
This, That and The Other One of nature's greatest gifts can also be one of a photographer's biggest headaches. Trees and plants can cause a lot of problems with photographs. This gets emphasized more in black and white but is still a major problem with color images. One thing is that you never want a branch coming out of somebody's head. This is almost unavoidable if the subject is placed in front of a tree.