What is the best format for a sponsorship proposal or deck?

Keep proposals brief and use bullet points rather than lengthy paragraphs. Sponsors review hundreds or thousands of proposals, so concise communication that hits the high points quickly is essential. Lead with what you can do for the company to help them sell products, not what you need from them. Consider sending a brief introduction letter first explaining your intention to submit a proposal, which can help garner attention before the full deck arrives.