According to Albert Lopez, a filmmaker based in San Francisco, there are six main things every aspiring screenwriter must keep in mind while working on a screenplay. They are the most important points because they are the most basic elements of any script. In no particular order, these are:

Know where you're going.

Don't use dialogue as a crutch.

Give characters playable actions.

Maintain structure/format.

Create obstacles for your main characters.

Second acts are hard to write.

Brandy Stoner (insert immature joke about her name here) at Absolute Write investigates further.