A good science fair project must be complex. Some of the best science fair projects are ones that are simple. You don't have to do something difficult or complex in order to have a good project.
Science is only about chemistry and physics.
Science is everywhere you go and in everything you do. Science deals with plants, animals, medicine, physics, chemicals but also TV, music, weather, basketball, aerobics and every part of life. Someone needs to give me a project idea. The best idea is one that you come up with. The best project focuses on your hobbies and interests.