Here is a condensed version of an article in “Entertainment Weekly” by Morgan Spurlock.
COOK UP THAT IDEA TO ITS TASTY END
Make sure you thought through the entire project; broke out characters, scenes, and key moments; and can answer any questions they throw at you. Have a friend play the always-questioning investor/executive to help hone your pitch.
BE PREPARED TO MEET ALWAYS QUESTIONING INVESTORS/ EXECUTIVES
Be prepared to meet always-questioning, confused investors/executives. Wake-up Call No. 37: Many times folks with lots of loot, power, and influence aren’t the most creative people. So help them get inside that warped Cronenberg-esque mass you call your brain. Put together storyboards, have drawings, play music, do a puppet show, anything. Well, maybe not a puppet show.
BE TENACIOUS
In order to get the meeting, you need to hit up everyone you know and even more people you don’t. One of my first pitch meetings came through the friend of a friend of a girl he knew who babysat an investor’s kids. You know a guy who knows a guy who washed the car of the head of development at Paramount. Call that guy.
MEET THE RIGHT PEOPLE
Meet the right people. You should know before you start knocking on doors who the most likely targets are. What network would put your idea on TV? What studio makes like-minded movies? What investor has put money into these types of projects? Find out, then chase them down like they just stole your wallet.
BE CONFIDENT
But don’t be arrogant. If you’re gracious and open, even if they say no, they will keep you in mind for other projects.
BE READY FOR THEM TO SAY NO
Even after all the success I’ve had, I still get more nos then yeses at pitch meetings. Rejection is a good thing. It’ll toughen you up. Sure, you may want to hug a pillow and cry because they’ve basically told you that your idea sucks, but wait until you get home to do that.
LISTEN TO THEIR FEEDBACK
Unless it’s wrong. Execs may not be the most creative bunch, but their input might actually make your idea better. Still, this isn’t always true. When I was pitching the docu-series “30 Days,” in which people immersed themselves in a new lifestyle for one month, one network executive said, “Wait a second. Who wins in this show?” I said, “You do, by watching.” He looked at me for two seconds and said, “Thanks for coming in Morgan.”
DON’T GIVE UP
I went to film school with some amazing, talented people who are now amazing, talented bankers and real estate brokers. They gave up on their dream. If this is what you want to be doing with your life, then suck it up and be prepared to fail, but do everything you can to succeed.
Gideon's Screenwriting Tips: Now You're a Screenwriter 
Good advice.