Kevin Kelly has a similar system than what I call a Service Design Library, he wrote a book with 400+ pieces of advice called Excellent Advice for Living.
In the episode 166 of the Knowledge Project podcast hosted by Shane Parrish, he explains from what makes a good advice.
These criteria can also be used to define what makes a good Service Design Principle. Here are some quotes of what he said about that:
"This is practicality. So I have several filters, I think through this, one is like, you know, do I really believe this?
This is something that I think really works. And then secondly, is it practical? Does it, is it actionable? Can, would it change how I do my day?
And thirdly was, was I'm trying to following my own device, uplift and be positive as much as possible."