We've got a simple 5step process to help you craft your letter. Below, you'll also find 3 unique templates with an example proposal letter for each.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. Identify the problem: Explain the problem that your food product solves or the need that it fulfills. Discover the secrets to creating a winning catering proposal in just 6 easy steps! Here are expert tips and a free template. Want to write a formal business proposal? Get a step-by-step guide, with free business proposal examples and templates. Easily customize this catering proposal template and send it online to impress your clients and get more proposals signed. A proposal letter is a professional document that introduces your business ideas to an important recipient, such as an investor or prospective business partner.