This guide to thesis writing gives some simple and practical advice on the problems of getting started, getting organized, dividing the huge task into less formidable pieces and working on those pieces. It also explains the practicalities of surviving the ordeal. It includes a suggested structure and a guide to what should go in each section. It was originally written for graduate students in physics, and most of the specific examples given are taken from that discipline. Nevertheless, the feedback from users indicates that it has been consulted and appreciated by graduate students in diverse fields in the sciences and humanities.