Have an outline/summary/treatment written out of your TV show. Give the development executives the documents to have in their hands, and quickly present your idea to them, avoiding the specifics and sticking to the basics. Know your show well, talk about the main idea, the story, the structure, the characters. Talk about what makes your show different from other shows. Perhaps use photos, posters or audio—any kind of supporting material that makes you and your idea stand out even more. Whatever you do, always be quick, specific and to-the-point.
Sell yourself and your idea. If you found yourself in that office pitching your TV show idea, then this means you have every reason to be confident and relaxed. Talk about your project with enthusiasm, keep them hooked. If you are unsure about a part of your idea, a character or a turning point, don't show it; it is important to have them believe that you are passionate about your idea on every level if you want to gain their trust.
Have alternative pitch ideas ready. If they don't seem to like your main TV show idea, do not stop. Give them something else to consider. Show them you have other things you are working on, and let them see you are serious about this. If your main idea, the one you feel most strongly about, is not working, then move away from it fast, before they lose interest. Be quick to re-adapt and be flexible.
If they pass on your TV show ideas, don't be disappointed. They have many ideas offered to them every day, so this is normal. What is important is to keep your positivity, not to give up, not to waste time, not to stop writing and to keep trying to pitch your ideas and to keep on going back to offer new ones to them every time. This way they will know you are professional, reliable and full of ideas.