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. Instantly draft and send a business proposal template to establish the terms and conditions between your business and clients.I like that this proposal includes helpful instructions in each section to help guide your writing. Most of the work is done for you. The minority business entity must be an Ohio certified MBE as of the proposal due date. A polite address. 2. A short introduction 3. Ohio Free Letter of Intent ( LOI ) Template. Utilize our Letter of Intent to formally express your desire to buy a product or service. Step 1: Initial Details.