Pictures of the volunteers at work, messages, and profiles of people you have helped, Pictures of people who have contributed to the success can all be incorporated along with a link to maybe your blog or a website will be ideal.
When celebrities or bigger brands associate with such a cause, it automatically gains significance and people are more aware. They ask the right questions before making a purchase and this is also success for the Non-Profit Organization.
If you find yourself always stuck with framing words which describe your work, use aesthetically taken pictures to convey your mission and how it actually impacts the people of an area. Take, for instance, a project where leftover food from hotels.