Sooner rather than later in your career you'll be invited to meet with TV development execs. So what do you do? First of all you need to know what kind of meeting it is. These meetings usually fall into two categories for.
MEET & GREET:
They've already read your work, like it and simply want to put a face to name. They want to know what kind of person you are, what programs you like and if you're going to be easy to work with. When I say easy, I mean someone they're going to be happy spending a considerable amount of time either in person, or communicating with.
What they're looking for is a polite, intelligent person, who is open to ideas and not obstructive or precious about their work. It's a collaborative process after all and they want to know if you'll take their notes as they are intended and use them to improve your script. You can object to notes, but only in a polite way, while giving valid reasons for why you think the note, or notes, won't work. Hopefully you'll be able to come up with a great alternative they'll absolutely adore. If you can't and they insist you make those changes, they need to know you'll do so.
PITCHING:
They've read your project outline, like it, but don't think it's for them... however, they want to hear more pitches.
Personally I think this is the most nerve racking meeting of the lot and this is how I suggest you go about things.
Prepare around six brief pitches. Keep your pitch to under a minute, giving the development exec the essentials; TITLE, GENRE, FORMAT and the project's LOGLINE. After that, if interested in the project, they'll ask you questions. If a question throws you, be truthful and say you don't know and ask if you could think about it and come back with an answer later. Guaranteed the answer will pop into your head the minute you step out of the door, so a quick email later with the answer, will solve the problem.
If the development exec starts fidgeting, rolls their eyes, fiddles with their phone, looks bored or distracted, bring them back into the pitch and ask them a question; "What do you think of the main character?" or something similar. Engage them. Don't lose them.
Don't forget to breathe. Try and speak calmly and clearly, not in a rush and garbled. If you find yourself rambling, take a quick sip of the lovely drink they offered you when you arrived and take a moment to collect yourself.
THE PROJECT PITCH:
They like your idea and invite you in to discuss it further. They want to know more. They want you to sell it to them. You do this by preparing.
If you don't know your project inside out then how are you going to pitch it well enough that the development exec gets the full picture? You need to not only know your characters as well as you know yourself, but you also need to know your premise and have closed all those potential loopholes in your project. I know this sounds simple but it's easy to be too confident before a meeting and not prepare fully. If they ask you a question you need to be able to answer it there and then, but if not, ask them if you could come back to them with an answer, as above.
And most importantly show enthusiasm for your project, show them you believe in it, and more than likely they will too.
Good luck.
Happy writing!