This encyclopedia was built on two things: teamwork and consensus building.
I'm an administrator, indie video game developer, and hopeless conversationalist. Since joining Wikipedia in July 2005, I have contributed to dozens of featured articles and reviewed countless featured article candidates. I also merged hundreds of lists and short articles during the Great Fiction Cleanup of 2005-2006; fan wikis were just taking off, so we moved a ton of fictional content off Wikipedia, tightened the remains, and finished with a nice, encyclopedic gloss. Sadly, some of the featured articles have been de-listed due to reference issues or sheer erosion of quality. It took a team of dedicated writers to work on those articles—in many cases, I was not alone. I was one of the youngest administrators back then, which is probably a bad thing. In my naivety, I tried to rewrite some guidelines...it didn't go too well, mostly because the site wasn't ready for the guidelines at the time.
I started the Star Wars WikiProject in February 2006, and was active in the highly successful, trend-setting Final Fantasy WikiProject throughout that year. In 2007, I shifted my focus to copy-editing articles, advising editors, and reviewing featured article candidates. After attempting to reinvent Wikipedia's treatment of fiction in late 2007, my activity became sporadic; time was limited due to my job, course load, and newfound passion for video game development. I mostly stick to sporadic copy-editing these days.
I encourage editors to collaborate with a powerful network of colleagues; nobody is perfect at every aspect of article writing. This approach ensures optimal quality while identifying the strengths and weaknesses of both the article and the user(s). Wikipedia is like an MMORPG: people of every "skill class" (e.g. researchers, copy-writers, copy-editors, policy aficionados) are needed if we want the best articles possible. Many people can "fly solo" and create decent articles, but they will burn out fast—especially if they are weak at either writing or taking criticism.
Volunteering on Wikipedia is a great way to build character and humility. It teaches people hard lessons that can be difficult to learn offline, such as: giving and receiving criticism, building consensus, acting selflessly, working as a team, and handling disputes. Why is this? Wikipedia combines the bluntness associated with internet anonymity with a constructive, common goal: people are more likely to be brutally honest (and less likely to be politically inclined) than they would be offline, and you can be assured that they are not trolling you. I've had some of my closest colleagues merge, delete, or rewrite some of my best work, and vice versa. Oh well; it is what it is. Learn something new from it and move on. When you can do that, you've learned a lesson that is difficult to learn in the sugar coated, participation trophy-riddled "real world".
Sango123 designed my userspace shortly before her disappearance in 2006. It was one of numerous surprises I received back then; I gave just as many, though. (Wikipedia was a different place—far more social, for better or for worse.) My favorite Wikipedian is Tony1, architect of the meteoric upturn in prose quality in 2006-2007.