The answer is simple. Write what your most passionate about. You number one objective as a new writer is to get noticed by the right people. Whether it’s a movie producer, studio exec or a literary agent, your goal is to wow people with your screenplay. The only way you’re going to do that coming out of the gates is by writing what you love. If you don’t, it will show on the page and you’re not going to impress anyone.
One of the biggest mistakes you can make is to write what you think will sell. As an upcoming writer this should not be your priority. Focus on getting people excited about your writing and build your career first. If along the way your script sells, consider it a bonus. The market changes all the time and what’s selling one month will likely be different another month. Buyers’ mandates change all the time. So don’t waste your time trying to predict and keep up with market trends. It doesn’t matter if it’s another zombie story, or a movie that will cost billions of dollars to make. Just write a great screenplay that makes the reader continuously turn the page, and you’ll succeed as a writer.
When you are deciding what to write, don’t begin until you have an idea that you are absolutely in love with. Otherwise, I guarantee part way through the process, you are going to be unhappy with your work and there’s nothing worse than having to finish a script that you don’t love, or quitting something you’ve already started. Take your time in finding a project you are passionate about.
You often hear people say, “write what you know”. This is a great mantra, but only if what you know is what you love. If there’s something out there that intrigues you but you know very little about, you can always do research. That’s part of the fun of writing. It forces you to learn things you never would have explored. If you ask any writer who has been commissioned to write a script, the biggest part of that process is research. There’s nothing wrong with taking the time to gather information so long as it’s something you are passionate about.