1. Always have a pen and paper (or a voice recorder, or a smartphone with a good battery). A pen and paper is best, as it’s living testament to your desire to capture ideas as opposed to just having a cell phone. Productivity nerds call this ubiquitous capture. The thinking is that your brain won’t give up the really good ideas if it thinks they’ll be wasted, so having a pen and paper is like a catalyst for creativity. If nothing else, it’ll maximize your productivity.
2. Pick a project and work on it until it’s done. The more projects you have, the less like you are to finish any one (there are other reasons to focus on one project)). Make sure your project has a coherent logline, a castable protagonist, and has an actual genre.
3. Have a trusted system in which to put your ideas. Remember, this is simplified because you’re writing one project at a time (see above). You’ll want to keep track of scenes, characters, dialogue, and other material that will feed your draft. Also set aside another set of folders for any idea you have that doesn’t pertain to your main project. Record it, file it, and don’t worry about it till your main project is done. I recommend Evernote or Workflowy.
4. Have a place to work. Most people have a desk, but for most people that desk is under piles and piles of bills, old magazines, and office supplies. A desk is a focusing tool for your mental energies. It is the physical representation of your control over your environment. If you’re feeling blocked, clean off your desk, there’s ideas under that clutter.
5. Write every day. It’s tempting to think that you can populate an entire screenplay by careful use of random ideas jotted down at stoplights, but the real work of writing is done while sitting at a desk, sweating out a dozen bad paragraphs for every usable sentence. Writing discipline is like a muscle, you have to work it every day. Set a daily goal and keep to it every day. If you can’t keep that appointment with yourself, this might not be the line of work for you. Make sure that you harvest the best ideas from your writing and put it in the trusted system. You don’t need to save everything, just the absolute best ideas generated by the writing.
These are the best practices that keep the writing machine organized and efficient. You’re working towards a beat sheet, and later a treatment, and finally a script. Sadly real writing will never be quite as easy as a simple “how to” guide makes it sound, but if you follow these best practices, you’ll be well ahead of the game.