1. Don’t make people think at all when they come to your site. Strive for simplicity and clarity. There should be no hard work to grasp who you are, what you do and why it matters—or how to help. 
2. Don’t post anything just to make your colleague happy. This is about the people who come to your site. 
3. Images are critical. Make them personal and relatable. Don’t post a photo a 10 year old can’t explain to you without reading the caption. 
4. Be interesting. The work of good causes is fundamentally emotional, and you want to leave a big impression that inspires.

(Source: nonprofitmarketingblog.com)