How do you write a grant proposal to start a small business?

Your first challenge will be to find grantors willing to invest in your type/ style of business.

Once you identify grantors, then you can solicit details for their requirements in order for you to qualify for their grant.

Writing the grant proposal simply implies that you've done enough 'homework' about your business and your potential market, so that you can address all the questions and situations listed in the grant proposal form supplied to you by the grantor.