I would not be doing you a service if I told you what you should do. My advice rather is to find a project on a topic that you are interested in. Remember that the teacher has a learning objective for assigning a project: that his or her students become engaged and look deeply into some science content. You must know already that the Education.com website has many science fair resources. I've also posted one below. I urge you not to take the easiest project to do but to challenge yourself - choose something that genuinely interests you so that you really learn something about the topic and about science. Good luck!