Charities make numerous mistakes when creating “case statements,” which tell donors why they should give, and other solicitations, said Tom Ahern, a Foster, R.I., consultant who advises nonprofit groups on communications.

Chief among the mistakes, he said, is that charities’ solicitations fail to answer three key questions in the minds of donors: why the organization deserves a contribution, why that support is critical now, and why the donor should care.

To show donors why they should care, he offered an example of a simple but highly effective appeal to get people to attend a fund-raising event to benefit a firehouse: “Come to our breakfast,” the appeal read. “We’ll come to your fire.”

One way to get a supporter to care, Mr. Ahern said, is to “treat the donor as a superhero. The more you flatter your donors, the more money you will make. You cannot overflatter donors.”

Some fund raisers make the mistake of thinking that donors go about making a gift in the same way as they would calculate whether to make a purchase, Mr. Ahern said. But “giving is not about a calculation of what you are buying; it is about participating in a fight.”

That distinction, Mr. Ahern said, helps explain why Barack Obama’s presidential campaign was so successful. Voters, he said, “wanted to get into a fight and win it. Think about what kind of fight you can get your donors into to improve the world.” As an example, he showed a nonprofit organization’s campaign to “fight junk science in our schools.”

Other common mistakes include using jargon and centering a case statement or solicitation around the organization and its needs, Mr. Ahern said. Doing so conveys “the case is all about you, donors are just like accessories,” he said.

Instead, he advised, “a case is really about offering the prospect a way to feel good” about what they will help accomplish with their gift. “A key motivator for giving is not need but opportunity,” he added.

To come up with effective solicitations and make sure that fund raisers center them on prospective donors’ interests, rather than their own, Mr. Ahern said it’s essential for charities to conduct interviews and other research to “see how outsiders feel about your organization.”

Mr. Ahern closed his presentation by telling fund raisers the things that good case statements are not.

“A case is not a detailed description of what you do,” he said. “A case is not a brochure listing all the things you do.” And, he said, a case is not read by a specialist who is paid to decipher what a fund raiser is trying to say. All fund-raising communications “should sound like someone talking.”