If I had to pick one 'secret' that I think is essential for any change to be successful it's 'Don't Fight Culture'. I think trying to fight- or wish away- culture is the prime source of frustration and failure that dooms a large number of well-intentioned and potentially very helpful projects.
To say that culture can't be fought is not to say that culture can't be changed. But change comes about through broad participation- and that kind of participation is not going to happen in a project that is seen as disrespectful or threatening to the essential that are embedded and encoded in each culture.
In addition to dooming a project to failure, fighting culture is totally unnecessary. No culture survives which harms its people in essential ways. All cultures are designed to support activities which contribute to the group's survival and well-being - or have in the past. It is very unlikely that an outsider will be able to see the myriad ways in which cultures connect and support their people. And changing them without understanding these things would be the height of folly- even if it were possible.