How to compose a letter to a friend to start a business?

Using a standard business letter format (link below), state your proposal and any specifics as your first paragraph, 'I am writing to you to propose...'

Use the second paragraph to explain the reasons (s) and expected outcomes for the proposal, keeping it short and to the point. Mention or list anything that may be attached to support the proposal.

Start the third paragraph with any important dates or time frame, if applicable; next provide the information necessary for them to contact you; and the last sentence is used to thank them for their time and/or their action.