This is very, very important. No plot, no film. It literally is that simple. The plot is like the tracks that your film or train will run on. The best way to get a decent plot is to watch other films. This will show you how other filmmakers have tackled the problems that you will encounter.
It is often helpful to choose some very obscure films that not many people will have heard of before. Then you can liberally copy as many of the plot elements that you like. A lot of people will tell you that this is cheating. Its not. Its called homage. Thats a French word and they know a thing or two about film making. Good use of homage will make you look like you know a lot about film and people will instantly respect you as a filmmaker. This is called the Tarrantino Effect.
Most people will tell you that you can use any plot in a short film. That is not true! Only a few tried and tested plot devices work really well. They include:
Guns. Your short film will really benefit from the inclusion of a gun - preferably two or three. A short film without a gun is like decaffeinated coffee. It may taste the same but it wont keep you awake. If you cant work a gun into the script a knife will make an acceptable alternative.
Drugs. People never get tired of watching films about drugs. The other advantage is that you can vary your storytelling perspective to either "drug culture is cool embrace it" or "drug culture is scary run away!" Bear in mind that it is a proven fact that all students are drug addicts.
Sex/Nudity. In this case female nudity as male nudity is just gratuitous and offensive. Sex and nudity are very important to maintain the interest of the audience. You wouldnt want a cappuccino without the chocolate sprinkled on the top would you? Sex and nudity in a short film perform much the same function.
Gay. Gay issues are always very topical. They are also easily adaptable. For example a Lesbian daughter who cannot tell her parents that she is gay. Or a Lesbian daughter whose parents cannot tell her that they are gay. Do you see how we can totally change the plot with just a few twists?
Again this is vital. Characterisation is like the passengers on your train. Without them the train is lifeless and empty. Unfortunately in a short you wont have the time to do proper characterisation. Instead why not really develop one character and leave the others a bit more sketchy? Most audience members wont even notice this simple diversion.
Alternatively, why not throw in a few stereotypes? That way the audience is presented with characters that they are already familiar with. Audiences like to see things that are familiar. Thats why Jim Carrey falling over and pulling a stupid face will never cease to be funny no matter how many hundred times he might do it in a film. Use stereotypes with caution though as some may be seen as offensive. For example suggesting that all black people are criminals is very offensive, where as suggesting that all students are off their faces on drugs 99% of the time is fine, as it is clearly true. Its a fine line. Tread it carefully.
This is an area where most people will get it wrong time and time again. The first principle to remember is "swearing is good lots of swearing is very, very good". A lot of people take the view that swearing is boring, monotonous and demonstrates a lack of imagination on behalf of the writer. This is just not true. The inclusion of lots of swearing into your short will instantly make it appear much more snappy and dynamic. Particularly if you use a few made up swear words like "muppet". I gave exactly that advice to Guy Ritchie and now hes married to Madonna I rest my case.
The best way to learn about camera technique is not to go to film school. All they do there is fill your head full of words like "semiotic analysis" and "Brechtian alienation technique". The best way is to use our old friend, Mr Homage. Simply watch a lot of different films and note down any cool shots that you notice. Then liberally apply them to your own work. Once again this is not cheating. Martin Scorcese does it all the time. A few shots/techniques that you will want to include are:
Trombine zooms: Most notably used in Vertigo and Jaws. Sometimes known as a trombone shot, this always looks good. Use it as often as you can. It is particularly useful when a character gets a piece of bad news as it visually denotes that their world has altered.
Tracking shots: These always look expensive. Youll want as many of these as possible. Editors will tell you that they can be difficult to edit together but those people are fools. Editors are born to complain.
Crane shots: See tracking shots.
Shutter stutter: As used in the battle sequences in Saving Private Ryan. This adds a staccato effect to the shot just as you would expect to find in real life. This therefore makes the shot seem more realistic. Use it for as many fight scenes as you can.
Variable speeds: A really good effect is when the film suddenly changes into slow motion in the middle of a shot. This is good for moments when an assassin as about to kill somebody, for example. This example can be enhanced by tilting the camera.
Jerky handheld POV: Denotes that the camera is now taking the place of one of the characters. This effect can never be over-used.
Black and white dream sequences/flashbacks: Audiences are stupid and will not realise that you are showing them a flashback or dream sequence. Make things easier for them by making those scenes black and white. In fact it is a good idea to try and work in as many different film stocks into your film as possible. Remember to list the stock codes in the script so that your actors know that youre a good director who knows about that sort of stuff. Do you think American Beauty would have won all those Oscars if it hadnt included some stuff shot on video?
Good directors always point at things. It makes them look like they know what they want. Point at things as often as you can. Pointing with both hands simultaneously is even better.
Always shout on set. It reinforces your authority.
As we have seen making a short is a tricky business. There are many different elements to juggle. But keep in mind everything you have read here and you wont go too far wrong.