Get yourself organized and have a plan! Make sure you have each candidate complete registration forms and a health history form as well as a waiver of liability. If you feel a Dr's note is required for clearance to tryout, request it. I make sure all forms are in and complete one week ahead of tryouts.
Also, when tryouts are over, provide feedback to each candidate - start with their weaknesses and inform them on where they can improve. I have found that because of the relaxed and professional way I conducted tryouts, I have girls who come back the following year to re-tryout! By providing feedback to these girls/guys, you assist them in developing skills that are lacking and fine tune those they have mastered.