I've got a 3 minute horror film to shoot, and while I've got an idea worked out, I am unsure of how to best layout a good storyline.

By this I mean that I don't know how to best layout the story so as to maximise suspense, interest, plot change points etc in so short a time, or indeed what kind of format to follow to make a short film like this work.

I would appreciate any advice or tips or information on er, information.

Welcome Dorian.

Let me first congratulate you on planning ahead! Good move.

I don't know the specifics of writing such a short film. I'd expect it should follow the general three act structure, just WAY shorter.

Keep the beginning and ending titles very short, just the title of the film itself would be fine. I might consider this format:

Beginning-45 seconds-introducing the protagonist to the antagonist

Middle-1 minute 30 seconds-the confrontation between the antagonist and protagonist

End-45 seconds-conclude the struggle between the two

Just basic stuff, hope it helps. Good luck.

they do follow the three act structure but it's kinda different. if you watch lots of them you'll notice the best ones follow this:

introduction to world/characters
conflich/tension/trying to resolve/resolution
discovery that nothing has really changed

mostly it's because any change that happens in the character in less than 10 minutes is percieved as forced or "fake", so most good shorts have an ironic ending, where the character thinks they won but they're still back on sqaure one.

it's true.

The best thing you can do is think about the ending first of all. Then pay attention on location and ilumination, horror movies are based on ambients, moods,textures.