One of the hardest things to maintain within a script is the use of active voice. Scripts should be written in present tense and avoid words like "is" and endings like "ing." For example, "Peter is jumping over the fence. He is falling down on his back and whining in pain," should be changed to "Peter jumps over the fence, falls flat on his back, and winces in pain." The second sentence could even be shortened to speed up the pacing. The easier and less wordy the script is, the better.
The active voice is always written in the action blocks. These blocks contain everything that can be seen on film. For example, things like "Peter feels frustrated" should not be written down. Remember the common phrase "Show, don't tell." After writing a first draft, go back through the script to eliminate this type of writing. Keep action blocks to a maximum of four lines, or even three. Add space in between to make it easier on the eyes while reading.
The key to writing realistic dialogue is by listening to real conversations. Listen to how people talk and hear how different it is from writing. People will often talk in small phrases and incomplete sentences, and interrupt each other often. Keep this in mind when writing for characters. Avoid writing dialogue that is straight to the point. The most successful screenplays feature dialogue with depth and characters who talk about their feelings without actually stating them out loud.
Slug lines are used to introduce each new setting in a movie and can be broken down into several elements. The start of the slug line always includes either "INT." or "EXT." for interior and exterior. The next part is the location, and the final section is "Day" or "Night." Save descriptions such as "Dawn" and "Midnight" for the action lines. An example would read: "INT. HOUSE--DAY." Specific rooms can be written as "INT. HOUSE--LIVING ROOM--DAY." Even though cars are outside, a scene inside a car is always written as "INT." as opposed to "EXT."
A montage is an effective way to show a character's journey, a time lapse or other event through a series of shots. There are multiple ways to write a montage in a screenplay .The first is as a "Series of Shots." On the screenplay, a person would write "SERIES OF SHOTS: PETER GETS READY." Then slug lines would follow with brief descriptions such as "INT. HOUSE--KITCHEN" and "---Peter eats breakfast." Another way to write it is with a "MONTAGE: PETER GETS READY" heading and action listings without the slug lines such as "---PETER BRUSHES HIS TEETH, --PETER EATS CEREAL, --PETER TIES HIS SHOE" and so on.