Don’t try and compete with the studio films. Your film will never look as good or as polished as their films, so don’t waste valuable time and money trying to making it look like that. Take your time and money and make sure you have a great script and give your actors more takes.
Your script is only a blueprint. Trust your actors and allow them to improvise. They know their characters more intimately than you ever will. You’ve got to worry about a hundred characters, they’ve got to worry about one.
Being a filmmaker/director is a collaboration. Trust your DP, production designer, costume designer. I encourage collaboration.
When sending your screenplay out to a movie star, don’t expect to hear back from them for at least three months. Which is a perfect time to get started on your next project.