There are two main factors that will change the way the plane flies: the
weight in the front, and the angle of the elevators. Elevators are the horizontal surfaces on the back of a plane that change its angle as it flies. That
said, every surface is important; a good plane will be beautiful and perfectly symmetric.
You can have great fun and learn a lot with paper airplanes flown by
hand. It is also nice to launch them with rubber bands. Nearly any paper
plane can be altered to make it rubber band launched.