In the future I hope to expand on this list. In general though, strive to follow the basics of the Unix Philosophy.
You should only know what your close friends tell you – http://en.wikipedia.org/wiki/Law_of_Demeter
Boring behavior is the new exciting – http://en.wikipedia.org/wiki/Principle_of_least_astonishment
(Doing) less is more – http://www.faqs.org/docs/artu/ch01s06.html
Rule of Repair: Repair what you can — but when you must fail, fail noisily and as soon as possible http://www.catb.org/~esr/writings/taoup/html/ch01s06.html#id2878538