There are no rules

Don't use "we." It pulls people out of the story. There's always a better way to do it. It's distracting. It's unprofessional. It's amateurish.

And then John August comes along and says, Yeah, I use "we" all the time.

*cackle* I love Hollywood.

It probably is true that the unsold spec writer should, all else being equal, stick to a fairly conservative writing style -- in other words, avoid all those things that everyone says will piss off readers. But if you're telling a great story, then your style doesn't really matter as much, does it?

On the other hand, if you're taking my advice, you have even less experience than I do, and I hate to be the one to break this to you, but your screenplay sucks. Write five more.