How to Write a Script
1. Get your story straight. Come up with a specific idea of what you want to happen in the play or movie. Create the premise and purpose of that story. What are the circumstances and what are the goals of the story and main characters involved?

2. Your characters will drive the action on the stage or screen, so make sure you make them interesting and innovative. It may not be necessary for you to develop all of the characters right away, but some writers need to have everything set out before they can begin working. Find your method and work with it.

3. Create an outline or treatment. Before you begin actually writing dialogue and script, it might help to create a basic roadmap of what will happen in your story. Sketch out a general plan and envision how events will unfold. This should be told in the third-person.

4. Maintain your style. Remember, scripts are all about action and dialogue. Make sure your characters speak realistically, and try not to mix styles of speech and vocabulary too much unless you are going for a certain effect.

5. Ensure that different characters have their own 'voice' based on their background, which will affect their word choices and dialect. This will stop your characters from blending into one another.

6. Set the scene. Don't forget to include important details such as time of day, setting, and actions of the characters in the scene. These are nearly as important as the dialogue that occurs.
7. Format your writing. Skip lines between one character speaking and a different one speaking, especially if you're handwriting it. This will enable those reading the script to distinguish between speakers more easily, and also allow space for notes.

8. Edit yourself. Continually revise your writing, and, if possible, show the script to a friend or adviser who has writing experience and can critique and improve the script as needed.

Script Writing
I am starting to research various ideas and scripts to help with writing my own script. As mentioned before I pretty much worship South Park.....the characters and stories are strange and hilarious while the meanings and morales are generally insightful and true. Overall the show is funny, crude, surreal and intelligent......all qualities that I appreciate. I would therefore love to create a script which held similar qualities but could be written for film (on a low budget) rather than cartoon. More recent series' of South Park have become increasingly intelligent and complex, full of messages and political views which are far beyond my intellectual capacity.....however earlier episodes had more simple premises such as mutant turkeys, aliens, zombies and talking Christmas poo which is more the kind of feel I'm aiming for.......stupid and surreal.

Here is an exert from a classic season 2 episode, "Prehistoric Ice Man".
Further South Park transcripts can be viewed here: http://www.angelfire.com/nf/spdomain/script.html

[on a hill]

[the scamps each have supersoakers]

Cartman [with an accent]: There's bound to be some crocs out here. I'll use my croc-call and try and bring them in. Bre-ni-ni bre-ni-ni!

Kyle: That's not how a croc sounds you fatass penis!

Cartman [with an accent]: Now I'm gonna kick my friend Kyle in the bean-bag and see what happens, boy crocky

[Kyle moves away and Cartman follows him]

Kyle: Get away from me, Cartman!

Cartman [with an accent]: Come here, crocky

[Kyle trips over a rock]

Kyle: Ah!

[Kyle falls into a hole]

[the scamps go over to the hole]

Stan: Dude!

Kyle: Help!

[Kyle hits the bottom]

Stan: Good job Cartman! You killed Kyle!

Kenny: {You bastard!}

Cartman: Well he shouldn'tve called me fat

Stan: Why the hell not?! That's like calling the sky blue!

Cartman: Well screw him, he's dead! Let's go look for crocodiles

[he walks off]

Kyle: You guys!

Stan: Hey, he's still alive

[Cartman comes back]

Stan: Kyle, are you okay?

Kyle: I think so. I Cartman out there?

Cartman: I'm right here, Kyle

Kyle: Cartman, you fuckin hunk of fat rat fuckin hunk of pig fuckin ass fat!

Cartman: Oh yeah! Oh yeah! Say that to my face, pussy!