Here are your experince points on the subject to help level up your game.

1. Think differently than your characters. Superman is good because of his morals. Lex Luthor is evil because of his. Take one or two aspects of your characters and skew it. Twist their ideas and warp them into a new, if not alien, set of morals. Make the players question their's.
2. Think BAD-ASS! Want to draw attention to your villains' villainy? Give them shinier toys. Give them bigger cars. Give them the girls/boys. Give them bigger hair. Make them transform into cooler things. Villains always get cooler clothes! Except for Batman and Gambit.
3. Think "street cred". Nobody wants to hear a giant backstory for an NPC. Don't waste your time with it. Let the villains' actions speak for themselves. Kill innocent villagers. Smash two planets together "just to see what happens". Push limits. Push buttons. But still give them a motivation. A driving force behind his/her actions. Players should have every reason to fear the moment they actually meet the head villain(s), let alone fight them.

To really go the extra mile, strive to have a villain who can blur the lines of morality. Some good examples are Alonzo Harris in the film Training Day, played by Denzel Washington, and Ozymandius from the Watchmen comics and trade paperback. Both are good uses of your time.

This is when a player is playing as if the character has full knowledge of the rules.  Here are your experince points on the subject to help level up your game.

1. Every time should be the first time. That's the ideal mindset, at least. Each time a new game starts, try to make it the first time everybody has played it. This cultivates a feeling of freshness and exploration, and with time, players may feel they've explored the world once they've actually explored some of the world instead of instantly knowing it before the game starts.
2. Describe it like *you* don't know what it is. When you say the word "goblin", a host of information comes to mind. Stuff like hit points, weaknesses, common stomping grounds, and their favorite Led Zeppelin album comes along with it. But when you, the GM, describe a "feral, tusked person, with green skin, molting and shedding what little hair is still on his head, drool dripping from his lower lip and reeking of month-old waste..." Well, that could be anything. Even a goblin.
3. Be in the moment, every moment. Try to keep players interested in what's happening now. More importantly, try to keep them interested in what's happening *next*. Now that you have them exploring this new game in a new world (so to speak), now make it worth their time. They'll thank you later.