"Options are bad" is the one that people often come up against and have the most trouble with. The basic idea behind this (for me) is that the software needs to be configurable but you should only present the user with the options they really need to care about - the rest of the time you make a decision about what is the best behaviour and you just implement that. This implementation should be done in such a way that hooks (actions/filters) are available so that a different implementation can be provided by a plugin.