Get as much information about the person to whom you intend to ask for help. Gathering information will allow you to choose the best tone for the letter and choose the most effective argument, find the "sensitive point". Especially if you intend to refer not to a faceless organization, but to a specific person (for example, by the famous artist, businessman or politician). Remember, your problem – all possible ways to interest a potential sponsor for funding.
Contact your potential sponsor in the letter maximum respect, but without excessive flattery and adulation. All the compliments have to be very diplomatic. It is best to specify in the letter the specific reasons why you decided to apply for assistance to the sponsor: the specific facts, achievements, achievements. In short, a detailed list of reasons why the organization or person has earned your trust.
Set a specific amount of money that you need, and why you need it. That is, the specific goals in detail. But not necessary to enumerate the necessary organizational costs. For example, if you intend to request financial assistance to start a business that will employ disabled persons, not to paint in the letter of assistance in detail the anticipated costs for items like rent of premises, salaries accountant, etc. it is Unlikely that such "prose of life" will appeal to a potential sponsor. There is no obligation to open up a business from scratch, even socially useful and socially meaningful for their own money.
Underline the letter in all possible ways your honesty and trustworthiness. Mention that you will be ready at any time to provide to the sponsor all financial records up to invoices on demand. And that he can be absolutely sure that not one penny of money given to them will not be wasted, or for any other purpose, except for those that you initially indicated in your letter.