There is Only ONE Rule
I attend the NY Book Expo every year, and every year I get to sit for a few hours and listen to famous authors talk about their process, and every time I come back home with a different point of view. Recently, I attended a breakfast panel where writer Barbara Kingsolver was discussing her process, the way by which she comes about new ideas, and how she approaches writing in a nutshell. She’ll have a remarkable personal experience (positive or negative) and decide to write about it. She has a lot of ideas floating in her head on a daily basis, and she finds the need to force herself to focus on one idea at a time as to not get lost in the writing process.
The Notebook is probably Nicholas Sparks' most well-known novel turned into a movie.
About five minutes later, Nicholas Sparks takes the microphone and admits to the contrary – he only has one idea, and when he’s done writing, he thinks that it will be his final book, and then – another idea comes into his head; when he’s done with a new book, he has no idea what the next one is going to be. Similarly – Stephen King is a very disciplined writer who has a daily writing routine. Aaron Sorkin, on the other hand, does not. He admittedly spends a big chunk of his day watching ESPN and searching for inspiration; every writer works differently. It doesn’t matter what your process is, all that matters is that at the end of the day when you greenlight a script – that script had better adhere to one rule, and one rule only: “don’t be boring.” That’s the only rule you are not allowed to break. Everything else – your approach, your methods, your style, etc. is flexible. There is no right or wrong approach to screenwriting, but there are many ways to go about it, and every- one will approach the craft in a different way. The cool thing about writing is that you learn about yourself and your craft with every new piece of material you work on. If you want to know what kind of writer you are, you need to write – and make a habit of writing every day and rewrite it until you deem it worthy.