Making films yourself is a good way to judge others' films.
Watching amateur films is a great way to learn more about movies.
As a non-professional film author, it is often not easy to gauge how the audience reacts to their own film. Movie juries at amateur film festivals offer help and advice for their own film.
As a juror, you have the task of politely pointing out mistakes and offering solution strategies. As with any craft, filmmaking has many rules to keep in mind. When judging movies, these rules are clues, however, the film always includes feelings. Expressing these feelings is sometimes a difficult task and recognizing these feelings is what makes a good judge or juror.