Brand seems to be a dirty word in the nonprofit/NGO space. Organizations shy away from it because "it's a private sector thing" or "it only applies to organizations that have money for marketing." The fact of the matter is, your nonprofit organization IS a brand. Just like any other company online, you need a defined tone & approach, you need to understand your peer and competitor landscape, you have to grasp the needs of your audience, and you must use all of those insights to create a branded social media strategy.
A brand is something someone can immediately recognize, something that brings a smile to a follower's face when they see an email or tweet pop up, something that turns your passive listeners and fans into aggressive supporters and advocates. This is why it's vital for nonprofits to embrace their brands. This is why brand matters, to everyone.
Branding shouldn't be forced. If you think of some of the top brands and the work they're doing on social, you'll realize that all of it seems to come very natural to them. The Starbucks, Red Bulls and Burberrys of the world get it and their social presences are organic. You can see that same kind of brand recognition with non-profit orgs such as The RED Campaign and Charity Water. Each one of them has managed to translate their offline/traditional brand into engaging, interesting, and meaningful digital content. They've also used their brand to create devoted fans and followers that essentially help promote their content on social for free.
Everyone needs to sign on. A half-hearted desire will never lead to success. Yes, it's hard to get everyone from the board of directors down to the digital community managers to agree to a brand or strategy when working at a nonprofit, but it has to be done. Without a unified voice, you don't have a brand on social--you've just got a lot of good content, that doesn't tell a story. A good way to get buy-in across your organization is to involve everyone from the beginning, hold interviews, register opinions, and keep everyone in the loop as ideas evolve.
It's okay for nonprofits to think like private companies. Yes, your mission is different and your end goals don't match, but that doesn't mean nonprofits shouldn't be just as tenacious and focused on brand buy-in from constituents and supporters. The people passively supporting your cause with just a "Like" now could be the ones who fall in love with your focused branding and become your aggressive advocates in the future.
Create your brand. Focus it around your mission. Stay true to your goals. Fight like hell to make it work...and don't forget to track it all when it does, because it will.