Liz writes in to ask:
I have a question concerning action lines and the caps lock key. I get that you want to use all caps when introducing a new character. That one's a no-brainer, but I've noticed that a lot of screenwriters use all caps to emphasize objects, actions and sounds. Are there any good rules of thumb to know about this practice? For example, if you use all caps for sounds, don't use it on action words.
The rule of thumb I always suggest is: "Make sure there aren't so many words in all-caps that the script is hard on the eyes."
I've read plenty of scripts where the writers tried so hard to make important actions stand out, that seemingly every third sentence on the page was either in all-caps, underlined, italicized or bolded. If you make the page that "busy" it tends to be cluttered and a lot harder to skim.
At the stage where most of you are, you're writing for the reader - in other words, don't make it hard for them to get though your script.
Sometimes you might want to put a sentence in all-caps to make sure that it stands out, something like:
as he glances into the room, he sees a wedding photo... with Wanda and Joe.
WANDA IS JOE'S WIFE! THEY'VE BEEN WORKING TOGETHER ALL ALONG!
While Jeff is preoccupied preparing the missile launch, Graham surreptitiously PRESSES A BUTTON ON HIS BELT. A light next to the button FLASHES off and on. A countdown.
The trick is to not overdo this. If you have a fair number of words in a paragraph all in caps and you find yourself putting a lot of words in all-caps, you might be inching up to the point where the reader's eyes are going to be weary.
There's also an older style of screenwriting where everything needed to be supplied by production (such as a prop or a sound effect) was in all-caps. That style is generally no longer used, so keep that in mind if you're learning screenwriting from older works like Casablanca.