A letter to request donations for your cause should be personalized, engage the reader and most importantly it should get you or your organization donations. The introduction of the letter should capture the readers' attention and get them acquainted with your cause and how it is evolving. It also helps to express gratitude for their role in the cause and to outline a specific project or initiative.
Make sure that you mention how vital their support of your cause is and how giving to you will benefit them and others when making the donation request in the asking portion of the letter. Here is where you will want to suggest donation amounts and tell what the amounts do for your cause. This helps to guide their donation and help you to more quickly meet the goal. You can also outline the consequences of ignoring your request. Don't put too much emphasis on the negative, but highlighting the consequences can create a sense of urgency.
As you bring your donation request letter to a close, be gracious and mention how grateful you or your organization is for their attention and donation. This means that you are trusting them to donate. Don't worry about being too formal either. A conversational tone is often well receive, and comes across as more sincere.