Brett Martin writes very thoughtfully about the demise of Sonar, his start-up that stopped. Most of his advice is sensible but his thoughts on culture resonate particularly.
All organisations will have a culture, whether that is deliberate or otherwise but the culture is not created by "hollow words" on what you want it to be, it is determined by the actions of a small number of individuals, in particular, the CEO.
Think of culture as a co-founder that is present when you are not. You are decisive, communicative, and respectful but it’s your culture that helps everyone know how to act when you are out of the room. Give that voice clarity and authority. The trick is to avoid hollow words.