Try to think of a nice plot or a scene and script it completely..try to do shot division before the shoot. This will give a better idea like hoe to caan a shot with ease and brings level of confusion to minimum.
Cinematography: When you are picking your crew for the film try to have a good cameramen who can handle and help u when u are in need. He should be in a position to understand the things what you think as a director and make into reality. And also while you are doing shot division just try to do with your cameramen since you will have some limitations with handy cams are with an HD cam since u wont have dollys and trolleys. If you have capability and imagination about lighting it is an bonus to the project. Try to learn about camera lighting fundamentals.
Editing: Many think that shooting a film is difficult but reality is that even if u shoot a film with an average look your editing skills will take them to next level. Editing is just like an heart to a film project. If u don have any knowledge about how to use an third party software then u can go for windows movie maker.Don't ever try to use too many transitions like Fade In/Fade Out, Dissolve etc., try to be precise with your content rather than decoration.
Other editing softwares u can use for editing other than windows movie maker are:
Wax
Virtual Dub
Adobe Premier
After Effects( Adobe Premier and After effects software's are complicated to use u should have basic knowledge about Photoshop to use these software's. And after effects is used to create special effects and graphics)
Casting: This is important and critical part of short film making. Don't ever compromise with your lead characters..
Usually u can shoot a short film with maximum of 4 characters on screen. Try to script something which will have only male characters try to avoid female leads since asking someone for this is very difficult if u go for a model it will be costly so try to avoid female characters. If u feel that u don;t have that problem then u can happily write your script without any limitations.
And try to pick someone only on their merit and acting skills but not on any other factor because he/she will be the persons who will be projecting your ideas on screen on behalf of u. So, never compromise.
Music: Try to compose your own music else try to find a friend who is good at it. Else, try to spend some money for this because u wont have to spend much money on other things.
Else, u will have some other option for this, there are some sites which can give u some music clips with different genres but u should be patient to pick them according to the situation so that that music blends with the scene. i will give the site names in my next post. This is time taking, but i can assure u if u have a nice music taste then surely u are going to hit the spot.Don't try to play film songs for background music..try to be creative.
Cams to Use: Now a days many are using even cellphone cameras to shoot short films. Please try to avoid this. But at the same time there is no need to spend lot of money on this. Try to get a Sony handy cam. Its enough and the price will be around 12,000-15,000. Else, find a friend who own that. If u feel that money is not a problem for u, try to go for a HD cam. But,they have their own advantages and disadvantages with both handy cams and HD cams.
Following all the above things u can surely bring professional look to your short film with no cost. Only things u need is nice crew, cast and a nice script. If u have any doubts please try to share.Try to rate the post so that it will help me to improve.