Recently I discovered MECLABS on YouTube, an independent research lab for marketing and sales. I must confess, that I highly agree with Dr. McGlaughins and his thinking. MECLABS concern less on graphical or visible issues in generell but on that what make a webpage really successful: It is a like a voice in the brain of your visitors that guides them by speaking to them.
Dr. McGlaughin has a great metaphor:
People don't buy from webpages. People don't by from companies. People buy from people!(5:40)
Ask yourself: Is your website a text or a speech?
Now think about it for one second. I think for myself, it is a very important difference so that I will definitly integrate some of their heuristic insights in my templates.
Although they do mostly research for commercial websites, you can apply the basic assumptions for non-profit websites.
Nevertheless I am very grateful that MecLabs continuously publish their marketing insights for free and discuss them in a webinar. I think I should give something back, so that I post a link to one of their videos and inspire You to engage in this stuff.