Partnering with an existing 501(c)(3) or nonprofit organization in your area is often the way to go. Are you already serving as a volunteer at your local school, church, or library? Community organizations often need people to help with fundraising and can benefit from your expertise in finding grant opportunities and putting together credible grant proposals.
Find new community partners by asking around in your community and by using tools like the Foundation Directory Professional (Online) , Guidestar , or Charity Navigator to identify groups who are interested in the same issues you are.