Branding is not just a logo. It is an image about you in the minds of prospective donors to your cause. Branding involves two issues: One, you must deliver communications that create the desired image. Two, you must get that communication in front of a wide enough audience to raise needed funds.
The first of these tasks involves a tasteful and relevant logo and a description of your cause and your own background that generates a sense of worthiness and credibility in your genuineness.
The second of these tasks is achieved through effective publicity. You select social and other media to reach your audience effectively, and use the best practices appropriate to each medium to communicate your message. Use actual case studies, images and video liberally.
Above all, ensure that the communications, including the visual elements, are consistent across all the media so that it becomes clearly associated with your campaign.
Successful branding as above is critical for the success of your campaign.