Here's some useful help from Equally Ours, a UK human rights organization: Talking about human rights (PDF).
It's about communicating about human rights issues, but it applies well to fundraising -- or just about any attempt to persuade people to do good:
- Educating with facts. Because people make decisions on emotions. Facts are more likely to drive them the other direction.
- Arguments about legal and procedural issues. They may matter, but your donors don't care!
- Myth-busting. When you try to bust a myth, you're more likely to cement the myth in readers' minds.
- International arguments. Like, "We should support this cause or other nations will not respect us." Your donors don't think that way.
(Thanks to Irish Charity Lab for the tip.)