In World of Warcraft, much like most games, guilds can be formed by players. These are then governed by players, controlled by players, and managed by players. The companies, and Blizzard is no exception, have very little to do with trying to manage these creations with the rare exception of conforming guild names to the Terms of Service (i.e. requesting players change offensive or inappropriate guild names).
Guilds serve in a variety of capacities and they don't always mean the same thing to each player.
For some, a guild is a place to socialize with individuals. As it provides a seperate form of communication via "guild chat," it serves as an effective means to ask questions, request help, and share news. For others, a guild is a means by which to make a personal statement such as "Dont Make Me Get My Main" indicating that this is likely a group of alternative, low-level side characters and if you mess with them, a higher level character will inevitably seek you out and exact vengeance. Yet, for most of the guilds that I have been involved with, guilds serve a purpose for the player to better their character.
Guilds generally serve a function: to level, to raid, to pvp, or to socialize. It can be one or all four - but usually a guild will have to prioritize what is most important to them. These four functions will often come into conflict and it is best for both the leadership and the members to have a clear understanding of what the primary, most important function of the guild is. That way, when resources are limited and the guild must focus attention on one aspect above all others, it is a justified action.
This was mostly common knowledge to me and I always tried to impress upon my fellow officers (administrative partners) in the guild that we needed to relay our justifications for our decisions to the guild. We needed clear, swift determination and to be working towards a common goal.
The first step to making a guild work is to set a strong foundation to build upon. We had a guild focus - rather an ideal that we wrote out like a vision statement for a company. We had a priority (to raid) that trumped everything else that the guild may be able to provide and made it infinitely clear in writing out guild rules. We had a method by which to make decisions and forums in which to communicate. We placed individuals in ranks who had been loyal and dependable.
What we didn't have was clearly outlined ranks and division of power. Later I discovered just how important this was and forever regret missing the opportunity to define what someone could do and - most importantly - couldn't do.