Learn how to write a business proposal in simple 10 steps. Based on our research and analysis of over 1.8 million proposals.In this article, we discuss how to write a business proposal letter and we offer sample letters and templates you can use as a guide. A letter of commitment indicates the signatory's intent to commit resources to the funded project as specified in the letter, should the proposal be funded. The letter request should not be more than two pages in length. Organizations should be able to sell themselves in the first paragraph.