To whom much is given...much is expected. That is a quote that holds true in many situations. Celebrities are people in extraordinary situations. Fame is often burdensome for the rich and famous. If you know a celebrity that you need to acquire a financial favor from, it's always best to proceed with empathy and caution.
Choose a celebrity that would have a personal interest in you and the cause for the financial help. The average celebrity has a mailbox full of charity requests. Research the celebrities in order to narrow down your options. A celebrity will give funds to causes that he supports, to be a part of a historical project that can lead to acclaim and recognition or as an investment in something that has probable profit. Keep in mind that you won't get something for nothing.
Consider who has a need for you and what you personally have to offer. Wealth doesn't only come in the form of cash. Think of what you have to offer a celebrity. Target specific celebrities that would need what you have.
Talk to the celebrity over the phone if possible. If you have a connection from a friend, this is very helpful. He can ask you questions directly about the project, and you can clarify what your needs are in the situation. If he trusts you and understands that you are honest and willing to work hard for the endeavor, your chances of success will have multiplied.
Create a proposition. It should clearly state what you need, what you have to offer and your detailed explanation of why this transaction will be beneficial to the both of you. Never try to con a celebrity (or anybody else, of course). You will get caught.
Mail the letter via priority mail. It's slightly more expensive than first class, but it is more official. It also may make your letter stand out from the crowd. It's also important that you do your homework. The celebrity may be out of town, on location around the world or swamped with personal things. It's never fair to get angry at a celebrity for a slow response. A celebrity's mail flow is often enormous, and your letter may have simply been marked as a fan letter prior to opening.
Be patient. While calling an agent to see if the letter arrived after a three to six week period is acceptable, further calls can be considered both an annoyance and a detriment from being taken seriously. Continuous calls can even end up with harassment worries. You want to keep it low key.
Send a polite follow up letter after six weeks. It is safe to assume that is enough time for a celebrity to have received your letter and have taken some sort of action. If she is out of town or otherwise engaged, she will not receive your initial letter or this follow up until some time later. You want to be clear that you are not putting pressure on in this letter. Simply state that you sent a previous letter, express your enthusiasm about the project and conclude that you look forward to hearing from her at her convenience.
Move on. If you wait for three months with no response, it's time to move on. Start with another celebrity that appeals to your sensibilities.
Don't ever assume that a celebrity will give you money. You are not his responsibility.