- Start with the "why;" you need to be able to clearly communicate why you want to create this particular game.
- Create, iterate, and practice your logline; this is the most important part of your pitch.
- Create a good pitch document; this is the most important piece of documentation you will create from a pitching perspective. Use the structure described in this article, but adjust it to the specifics of your idea
- Do not only pitch the idea, but the probability of you pulling it off as well. The team behind the execution is a crucial part of the pitch.
- Practice. Your. Pitch.
source: https://gamecareerguide.com/features/2028/how_to_pitch_a_video_.php