How do you paint with a group?

[janey]

I joined my school's art club and our first project is to paint a scene supporting school spirit on the (large) windows in the cafeteria.

I have never worked on an art project like this with others and I'm wondering how we are supposed to keep the painting uniform in style? How does this work? Obviously I'd paint a tree (even if it was already outlined) differently than my neighbor- so what's the secret?

Thanks for replying!