Agree with everything Alex said except the max 3 line rule. Generally, it's max 4 unless you're writing a comedy or a script that requires quick burst of words to make the read smoother.
For new writers, you'll undoubtedly get comments where you're told not to put 'we' or not to direct the shot, which may seem like a standard rule but trust me, it's just preference. If a reader is forcing you to change your voice, I would ignore the comments about it. Eventually, you'll realize yourself what works and what doesn't but if somebody asks you to not use a certain style in your writing without good reason, it's best not to listen to it.