Congestion pricing has been advocated for a long time as an efficient means to reduce road congestion, without much success in practice. In the last few years, however, congestion pricing has been introduced in various forms, with London and Stockholm attracting the most international attention, starting in 2003 and 2006, respectively. The Stockholm experiences have attracted widespread attention from many cities that consider introducing similar schemes., and the people involved in the development and evaluation of the Stockholm system (including the author, who was responsible for the design of the charging system and forecasting its effects, and subsequently chaired the Expert Evaluation Panel) have acted as advisors to many policymakers from cities and countries all around the world. This paper is based on these experiences. A number of questions repeatedly surface in discussions with policymakers, politicians and planners. A number of facts and insights repeatedly turn out to be especially relevant and interesting, and to a certain extent surprising. The purpose of this paper is to summarise these questions, facts and insights, for the benefit of cities considering congestion charging schemes.