There are many ways on how to make captivating short films. But I only am going to share you what I think is effective. A short has a qualifying length. The best length for a short film is at most 10 to 15 minutes. Try your best not to go over 15 minutes. Meanwhile, less than 10 minutes is very optimal so avoid these things. Too much exposition is not good. Make your exposition efficient by making it simple. Explain the important details quick.
In fact, this is the tricky part in doing short films. It is the part that takes time explaining the backstory or any detail that is needed to fully understand what you are watching. Overawed exposition is something a film maker wants to avoid more than anything. However, a lot of inexperienced film makers make this mistake by throwing in too much expositional dialogue, not knowing that they had already spend much time without even getting into the highlight of the short film.
Also, short films are better medium for experimenting. It is a way to practice the techniques that you did not mater yet. As an advantage, short film contest can make you money and can lead you to be an Oscar nominee. Short films can be used to start a feature. It can be used to enticed investors and viewers. Doing this, take a scene from the feature that can work on its own. A scene that gives a good idea about the project, and shoot that scene as a short film.