Advice for the potential statistical consultant

Many of those who have never practised statistical consulting seem to view it from one of two extremes: a trivial exercise that any statistician could do, or an extremely difficult task occasioning extreme anxiety. Of course, the truth is that it lies somewhere in between. I will consider various aspects of statistical consulting, including the characteristics of a successful consultation, the necessary knowledge, skills and attributes of the consultant, things to do and not to do, and the pleasures and frustrations that one can gain from consulting.