Become a closet editor. Other than music, it's the single most effective way to impact a piece of film.
Last month, Variety published "Why Editing Nominations Predict the Best Picture Oscar" with some of these interesting factoids:
Only 9 films have won best picture without at least a nomination for editing.
Of the 61 films that have won Best Picture, 32 have won Best Editing.
Jay Cassidy who co-edited American Hustle says, "There's no such thing as a good scene in a bad movie...If filmgoers are moved by the story and emotion in the film then it's probably well-edited."
If you're not familiar with how editing works, or why it's important, start learning. Here's one of my favorite scenes from The Social Network, for which Kirk Baxter and Angus Wall won the Oscar. Notice how the edits begin to match the pace of the athletes. The cuts almost become their heartbeats. That's not just a happy accident.
The Social Network "Henley Sequence" from a52 on Vimeo.
Of the 10 movies nominated for Best Picture, here are the trailers for the five Best Editing Nominees (but don't confuse film editing with trailer editing - they're done by different people):