The 180 Degree Rule
Have you heard the phrase "Crossing the Line"?
It has to do with the 180 degree rule. Knowing this will help you from confusing your audience when cutting from shot to shot.
This is a rule that is often misunderstood. I've been at several real world shoots where the director and the director of photography are arguing about whether or not a certain camera position breaks this rule.
(Side note - The director of photography is always correct! But try telling a director that haha.)
But thankfully, after this lesson, you'll know exactly what you're doing.