Make a list of groups that you could approach to fund your project. Large companies are often required to distribute funds to the arts. If you are shooting your film in a local area, see if businesses around your shooting location would be interested in funding at least part of your project. There are also many film organizations, like Women Make Movies, that are looking to help new or creative talent get sponsored.
Draft a letter that you can send to potential sponsors that tells them about who you are and the project that you hope to create. It should outline what your movie is about, your experience as a filmmaker and a description of what you hope to achieve by creating this film. The letter will allow the potential sponsor to become comfortable with you. This first impression can also be made in person, but you will still need materials to leave with them.
Collect data about the potential viewers of your film. A sponsor will want to know that they are reaching the demographic that they are targeting. Analyze statistics from other films that are like yours; or the typical attendance of any film festivals you plan to show your finished project at. This data will be helpful in convincing the group that they are maximizing their money investing in you.
Create a budget that will allow the sponsor to see how you intend to spend the money. Some groups have restrictions on what the money given can be used for.
Provide a presentation to interested groups that will specifically explain what the group should expect to receive as a result of a sponsorship. Some groups will not need anything in return, while companies may ask for you to add product placement or to pair their product with your movie. Offer banners and signs at film-related events to smaller sponsors.
Write a thank you note to any group that takes the time to consider your presentation. Hand-write the note instead of typing it, to make it feel more personal. Let the group know that you are anxious to hear from them.