The experiment is one of the most important methods in science and is also one of the basic ways of approaching a science project. To suit an honors science course, your experimental science project must either approach an old topic from a new angle or address an entirely new topic. For example, experiments involving plants have been done to death, but you can still create an innovative plant project if you set your mind to it. For example, try growing plants in strange situations, such as on a rotating turntable. You may find that the plant's roots grow in a strange way.
The observational study is a common science project because it is easy. You only need to observe something and record your findings. You can make an observational study appropriate for your level by observing something no one is likely to have observed before. Most people go outside looking forward; you can try looking downward. Make observations of what's below you: how much life do you find on different types of surfaces? Are there more ants present on the grass, dirt or concrete? Try using a creative perspective to employ such an observational study.
Correlational studies investigate the relationships between variables. Most correlational studies inexperienced scientists perform investigate obvious relationships: race and height, study time and GPA, and gender and telephone usage. For an honors-level correlational study, think of two seemingly unrelated variables and investigate their relationship; the findings may surprise you and those you are presenting the project to. For example, investigate how race relates to the amount of daily water intake, how study time relates to music preference, and how gender relates to diet.
Models are common projects, especially in science fairs. If you choose to create a model, you can add innovation by creating the model from an entirely different angle. For example, instead of creating a stereotypical solar system model, create one from pre-Galileo periods -- those in which people thought the earth to be the center of the solar system. Show how this model makes no scientific sense in terms of explaining day and night, seasons and years.