And you know what? It's complete, utter and total bull.
No one who actually has anything resembling a career has just one good script, or worse, WAITS until they sold that one script to write more. It's like if a baker only makes more cakes after just baking one, or a dentist who only does cavities and nothing else. I, for one, am always frustrated when I see well meaning folk pop up on forums and Facebook writing groups with a script that they say they've spent 'years' on. An A for effort, yeah, but it's also obvious they haven't written anything else in that time. They put all their eggs in one basket.
Being able to generate multiple ideas and then write as many scripts (film, TV, radio, stage, short, webseries) as possible is vital to making it. Each one presents a new challenge for you to grow and improve as a storyteller. Your characters have more dimension, your structure gets tighter, your pacing faster, your dialogue sharper. It's slow, but worth the slog if you really want this bad enough. As Frank Darabont said, ''Everything is self-applied effort in life. You don't get anything easily.''
Alright then, so what can you do?
- Write down everything. No seriously, this is not some throwaway guff from 'professionals': it's true. On paper, your phone, in a Word document, on a napkin, just write down any idea you have. Doesn't have to be deep or detailed or eve immediately obvious: something as random as ''zombie ducks invade Cardiff'' might have something in it. Always have a little ideas folder or cache handy: it may save you in a moment of the dreaded 'block'.
- Do one pagers: again, don't worry about perfection. Just write a rough outline in three-four paragraphs, detailing the very broadest strokes of what you'd like to do with the idea. Additionally, do the logline: that super condensed, to the point version of your story can be super helpful in finding the heart of the piece.
- Exercises: a lot of screenwriting books and websites have these - very quick, usually 5-10 minute challenges you can do to help you come up with something (also good for block-busting). Could be building a character in layers, could be a brainstorm or mind map, maybe even just write a random scene with two characters. Anything can lead to something.
- Read non-film stuff: A trip to the library or, if you're just feeling mega-lazy, Wikipedia, can yield all sorts of possible inspiration. News, politics, history, art, science, all can plant a seed of something in your mind. Who knows, you might find great drama within the confines of American corn production.
Writing is hard. Very hard. No formula or beatsheet will change that, and if you really love it, you'll push yourself. Getting your first script finished is a wonderful feeling. Knowing people like it: even better. However, staying married to past glories is dangerous: say your script does the round at contests and companies, and no one goes for it. What now? If you just hawk the same thing year after year, you'll look like a one-trick pony who never had anything interesting or unique to say.
I speak from cold, hard experience. Look for yourself:
http://verystrangethingsanimated.blogspot.co.uk/
You know why else this is handy? If you get a pitch meeting, you may well be in a scenario where they like your writing, but the script's just not right for them at that moment (I have). They'll ask, what else?
See how helpful this backup can be? But if you're still not convinced, listen to working screenwriter Mark Sanderson and his experiences.