Learning to write well is an essential part of becoming a successful researcher. Unfortunately, many researchers find it very hard to write well because they do not know how to view their text from the perspective of the reader. In this talk, we present a simple set of principles for good writing, based on an understanding of how readers process information. Unlike such platitudes as “Be clear” or “Omit needless words”, our principles are constructive: one can easily check whether a piece of text satisfies them, and if it does not, the principles suggest concrete ways to improve it.