Fun for All

Including the Referee
Campaigns can end prematurely for lots of reasons. One of the most common is someone isn't having fun, maybe several someones. If one of those not having fun is the referee, the campaign is probably doomed. The referee has a strong influence on the tone of the campaign and an unhappy referee sets an unhappy tone. By contrast, a happy referee can inspire players and enthusiasm is contagious. It is certainly not all about making the referee happy, but neither should the referee's job be one of thankless suffering and work, always putting the needs of others ahead of their own.
White Box introduced the world to the new type of game and most of us were happy just playing. It was fun because it was new and a constant discovery. Most of us took turns refereeing in order to share an adventure idea we had or simply to take our turn behind the referee screen. Eventually we started to analyze what made some games better fun than others, why some campaigns seemed to last longer and why nobody really wanted to play when so-and-so was referee.
Fairness and player agency are goals which have found expression in more recent discussions about game design and mechanics. Some rule editions have become tighter and more restrictive in an effort to mitigate the effects of a poor referee. Personally I find them generally less fun to play as they are too restrictive for my taste, disallowing the flexibility to be imaginative in problem solving and feel too "mechanical". The rules lite approach may be more risky regarding what happens at the table of a poor or inexperienced referee, but also it's more rewarding when run by a gifted referee as the rules seldom get in the way.
Experience is the best teacher for a referee, but today we also have access to some very good advice on the art of refereeing an RPG. Paying attention to the desires of your players, listening to what they want in their game and how they would like their PCs to be challenged is a good start. Action and pace are important and giving players at least the impression that they have meaningful choices. Setting limits is also good referee advice. In the spirit of old school gaming, players should not coerce the referee into making things too easy, allowing the PCs to become too wealthy, too powerful and too destructive of the milieu. Such behavior really ends up making the game less fun for everyone eventually. Success in roleplaying games really boils down to everyone having a good time. If everyone is laughing and enjoying the game, then you are doing it right.