TAGFEE is a very powerful guiding principal from Rand at SEOmoz:
I think the thing I underestimated the most when building Infinity Softworks in the early 2000s was how much thought needed to go into the company itself. When working with more than one person, serious thought needs to go into what kind of organization it needs to be, what will be the guiding principals, etc. And then it is even more work to keep enforcing those.
Back then I just hired and figured it would sort itself out. Now I realize that good company culture is planned as strongly as the product.
(Thanks to Brad Feld for the link.)