1. Avoid spoilers. They're called that for a reason. If you want to play a game and have fun, don't ruin the experience for yourself by reading the wiki first.
2. Enjoy the game at your own pace. Especially in MMOs there's a pressure to be at the bleeding edge of current min-max builds, gear sets and meta-strategies. Unless you're a power gamer willing to pour hundreds of hours into the game for the best loot and/or exp, just sit back, relax and enjoy yourself instead.
3. Explore the games. Look for easter eggs. See point 1.
4. Try older games from a bygone era. There are a few channels, some legal, some less so, that allow you to play games from the past few decades. Why not find out every decade's top ten game list and try each one?
5. MMOs are only going to satisfy you if you enjoy participating in a community. Single player games offer far better graphics, controls, stories and cutscenes over MMOs, but lack the human interaction that make MMOs so addictive. Voice chat software either built into the game or as a separate program will greatly enhance your MMO experience. Recognizing your friends by voice alone really adds to the enjoyment, and lets you chat during boring grinds inherent in any MMO.
6. Cheat codes and mods are only for when you don't care about the game experience any more. Sure, it's fun to mod Skyrim with busty naked women, but it also spoils the experience for you. I only mod a game I've completed vanilla, so if I see something I want I'll just have to wait and play with it on my second time through.
7. Go look at game trailers outside your regular genres. See if something appeals to you. Doesn't need to be triple A titles, but they usually have the best to offer for eyecandy.
8. Don't spend all your free time playing video games. You're likely to get bored of the same old thing over and over. Split your recreation time into different activities. Game for an hour or two, then read a book or watch a movie. Even a sport or exercise a day or two per week instead.
9. Play with friends. I hate racing games but will happily play them if I'm sitting on my friend's couch drinking beer with him. It's about the social experience, not the game itself.
10. Losing is fun! Since you're on the Bay12 forums I assume you have played Dwarf Fortress and understand this mindset. Games don't need to be beaten, and some have no possible victory condition anyhow. The premise of a game is simple: you exchange your time for fun. No real value is gained when you play a game. Your imaginary items and money are actually illusions. Just play for fun, not to win. Of course, winning is fun too, but don't be upset if you don't. Simply enjoy yourself.