Unlike some of the other rules of traditional screenplay formatting, the rules of capitalization are not written in stone. While each writer's unique style will influence their individual use of capitalization, there are 6 general things that you should capitalize in your screenplay.
Of the six uses listed above, #6 ("Integral sounds, visual effects, or props that need to be captured in a scene") is by far the most disputed. Keep in mind that not every sound, visual effect, and prop needs to be capitalized. The number one priority is that your script is as easy to read as possible. Ask yourself, "Does capitalizing this word enhance the reader's experience?" If the answer to that question is a thundering "yes," then capitalize. However, if your answer is "maybe" or "no," it is best to not capitalized. Keep your use of capitalization for this scenario limited to a minimum. NO one WANTS to read AN ENTIRE SCRIPT that IS PLAGUED with CAPITALIZATION. Less is more!
There are a number of great blog posts and forum strings on this topic. Check them out here for more!:
What are you thoughts on capitalization? Feel free to share in the comments below!
Cheers to writing!