Take time to think about the project, presentation, and the materials needed to have a neat, attractive display. Plan to photograph appropriate aspects of the investigation for later display on background posters. Some teachers require literature searches, written reports or in-class presentations in addition to the investigation itself. Many science fair contests require that an oral report be given to one or more judges who can then ask questions about the investigation. Listen to your student perform a practice run, and try to anticipate questions the judges may ask.
Teachers can help by providing judging criteria for students and parents to consider.
It is helpful to keep a database of ideas from year to year for students to use. If you are in charge of organizing a school fair, you may want to model your rules after the district or state rules. That way students will already be familiar with procedures when competing at various levels. Keep tabs on student project plans and guard against illegal, dangerous, or other problematic investigations. Enlist the help of colleagues in preparing your students.