Often regarded as (one of) the best referee(s) of the 20th century, Pierluigi Collina took charge of many great matches, one of them was the 2002 World Cup final in Yokohama between Germany and Brazil. And there were finals of the Champions League, the UEFA Cup and the Olympic Tournament.
Apart from being a very good ref, Collina also wrote at least one book about it and managed to use his popularity - and his famous bald head - to make some money by selling Opels on tv. And why not? But Opel was also the Milan sponsor, a fact that may have prompted Collina to retire a year early.
In his book Le mie regole del gioco ("my rules", not "the rules") Collina writes a little bit about his life, he mentions some matches and tells us a lot about his thoughts on how to be a good referee. Because he was such a good referee all other referees should take notice (not because he is such an interesting writer, which he isn't). Collina turns out to be a stickler to routines. When he arrives before a match, how he gets there, what he eats and drinks, when he does his training, how long he sits concentrating, everything had to go according to his rules. The Italian sounds a bit autistic in the way he really needs to do all those things in the exactly right way (Collina sometimes sounds like the character Sheldon Cooper, in the American sitcom The big bang theory). Collina writes about how he hates dining alone in a town the night before the match. And how he hates sitting at a table longer than necessary even when his assistants join him.
A large part of the book is about his preparations before a match. Collina always tried to find out as much as possible about the teams, the players, the style of playing, the history between players. He knew beforehand what a coach would do when his team was a goal behind, he wanted to know which leg players preferred to use (a lefty on the right side is more likely to cross into the midfield, and when a lefty on the left side was on his way to the goal line, Collina knew he could start watching the players standing in the box.)
All these facts he taught his assistants on a white board.