1) Thou really ought to try and see all of the elements before the mix. Surprises = Time = $$$.
2) If thou hast ignored the first commandment, thou shalt not panic. We can fix it. Fixes = Time = $$$.
3) There is hopefully only one director. Thou shalt give your honest opinion but bow to his/her will. Arguments You Cannot Win = Time = $$$.
4).Thou shalt not talk incessantly on thy telephone while the mix is in progress. We need to hear the film. Get thee to another phone please.
5) Thou shalt consistently overpay your Sound Supervisor/Designer. He/She deserves it.
Amen to 5. :)
Steve does rant just a tad, but what do you expect from overworked audio folks? Anyway, filmmakers both rookie and veteran would do well to read and heed this...screed (sorry, couldn't resist).
Link to the article, via ifp.org.