What is the character?
More often than not, the rogues that are brought up in discussions of the archetype are characters like Han Solo or Malcolm Reynolds, fundamentally decent people willing to break the rules as it suits them. Reynolds is pretty close to the archetype, but even he distills the essence a bit, because a rogue's true allegiance is to no one except himself. Rogues want something, and while that something can range from money to fame to a chance at a thrillride, no rogue cares much about the human cost beyond what's absolutely necessary. Any political motivations or personal attachments come in second to what the rogue wants.
That being said, rogues also aren't just out to hurt people or take from people. The stereotypical lawyer is, in many ways, a rogue -- he only wants to get paid and doesn't care whether he's defending a client who's innocent or guilty. All he cares about is the money and the victory, and the rest is window-dressing. Rogues are selfish, yes, but not nasty for the sake of cruelty or kind for the sake of generosity. A rogue will not kill a man in Reno just to watch him die, but he might kill a man in Reno to steal that man's car and avoid any future entanglements.
What's the angle?
Amorality suits adventuring just fine. All of the pesky shades of gray, asking whether it's really correct to march into the homes of other living creatures and kill them for no real reason, even asking whether or not violence is the best answer to all problems -- all of this slides off the rogue's back like water off a duck. The rogue's moral compass points only to what he wants and how he can get it with the fewest long-term consequences. Adventuring is basically a license to do just that with a variety of fringe benefits.
Most rogues are only amoral to a point, having certain lines that breed the difference between self-reward and outright cruelty. Some really have no moral compass, which leaves you with a rogue only a few steps away from blatant sociopathy. Others have found themselves in a more amoral position due to a combination of disillusionment and unfortunate circumstances. Still others have grown up without ever really needing to develop a sense of morality beyond "what I want is right," and being out in the bigger world is what will help bake in some human decency. There are many ways to go with the concept, many of which have been explored and many of which haven't.
What makes it interesting?
A true rogue lives by his own rules and often creates interesting roleplaying situations just by being around. Not only do characters have to convince him to stick around, but he has to bring something useful to a group. Usually that's in the form of both connections and a willingness to go outside the boundaries of socially acceptable methods. A holy knight might disapprove of a rogue's methods, but it's hard to scoff at the results, and when you get right down to it results can matter more than morality on occasion.
For a player, a rogue is the chance to break whatever written or unwritten rules exist about fair play or decency without tripping over into full-on sociopath territory. The rogue doesn't feel much loyalty toward the roleplaying group as a whole, and as such can say and do things without the same restrictions as other characters. He also gives a chance for you to at once make a character who is well-connected with lore and NPCs while having a built-in excuse for limits on what he can do.
What should I keep in mind?
A rogue is not cute and cuddly. He will often wind up working with other people, frequently to no seeming reward, but he's always ready to take off for greener pastures if things go too far south or diverge from his own interests. Even after he's more or less along for the ride, your rogue should still act in a way that reminds people he's looking out for number one through all your adventures. Do remember, however, that you don't want your character constantly at odds with everyone else in the group. You need a reason the rogue continues to work with people, but it doesn't have to be an elaborate one.
The fact that a rogue has a free pass to be a bit more selfish than usual does not excuse any selfish behavior on the part of the player, naturally. As ever, caution should be the byword here; your character might argue that a piece of loot is his by right or that the party leaders should be paying him to stick around, but you as a player should move on from that fairly quickly. Don't push into uncomfortable territory, and if you start to tread dangerous ground, you can always handwave it off by promising to invoice the party later or something similar.
Perhaps most importantly, rogues can wind up being just as heroic as the people not motivated solely by self-advancement. They will just do so for different reasons and quite possibly have to be dragged down the route of nobility kicking and screaming.
That's our archetype for this week, and I can only hope it goes over as well as the first one (for which I received some nice letters of praise and two letters offering me genuine Rolex watches at a discount). Comments may be left in the newly improved comment field, naturally, or sent along to firstname.lastname@example.org. Next week, it's the promised topic from three weeks ago, diving into the field of enhancing your roleplay out of the game proper.
Every Friday, Eliot Lefebvre fills a column up with excellent advice on investing money, writing award-winning novels, and being elected to public office. Then he removes all of that, and you're left with Storyboard, which focuses on roleplaying in MMOs. It won't help you get elected, but it will help you pretend you did.