Star Wars Galaxies (SWG) is an MMPORPG -- a Massively-Multiplayer On-line Role-Playing Game. It provides a fascinating and engrossing roleplaying environment, where you can start a new life in the fictional world of Star Wars. But, clearly, the Star Wars setting is a bit different from others that you might know from previous roleplaying experiences. This essay attempts to answer the question, "How does the Star Wars fiction affect my roleplaying?"
When you're working on the history in the Star Wars environment, it's important to remember that, to be believable and enjoyable for your fellow roleplayers, your history has to avoid conflicts with the past, present, and future Star Wars story. The story also needs to recognize the fact that you are (for the most part) just one snowflake in a blizzard -- unique, sure, but without any special capabilities beyond those of millions of other characters (player characters or otherwise) in the world. In general, the Star Wars galaxy is just a setting -- the chances that your character knows Lando Calrissian is about the same as the chance that you personally know Billy Dee Williams. Don't assume that your character is Force Sensitive or a lost clone of Jango Fett. These things may be theoretically possible in the setting, but they make your story harder to believe and incorporate into other roleplaying, and make it more likely that some new or previously overlooked fact of Lucas's story will make your story impossible. If you are tempted to take this route, be very careful not to tread anywhere that the official license might already have claimed. Also, take care that your character's backstory does not conflict with other characters' backstories. It can be a lot of fun to coordinate these stories with friends, and this will also happen naturally -- but be careful not to assume too much in advance.
At the same time, you should leverage parts of the existing fiction (and the contributions of other players) where appropriate. If you check out the story and verify the timing of events appropriately, it can add instant recognition to parts of your roleplaying -- say, identifying yourself as an aging veteran of the Battle of Naboo, or someone who used to enter the podraces on Tatooine back in the Old Republic, or a traveller from Alderaan who just happened to be off-planet when the Death Star struck your homeworld. But if you do this, do your homework -- get your age right, know where characters of your species were at the time of the event you're referencing, and so on. You don't have to tell everyone these details, but having them right will help you and everyone else enjoy the story without having to worry about whether it's "possible" in the world we're playing with.
Likewise, be careful about taking roles that aren't readily available in the game's design. If done correctly, this can be a rewarding challenge (a good example in Star Wars might be "Tusken Raider"), but in general you should avoid, say, attempting to claim that your Trandoshan is half Human. Or, worse, half Elf (please don't try this, I've seen it before and it's just sad). Also, when you're developing a backstory for your character, remember not to make assumptions about your character's luck, or power, or skill, when such things are typically limited by the game itself and therefore beyond your control to manipulate or rely upon. You can of course reference these details as your character develops (and has a lucky streak, for example) but you shouldn't assume them in advance.
One important note: if you encounter a fellow roleplayer who doesn't seem to be following your idea of good roleplay practices, remember to react in character. Sometimes, it's just a matter of adjusting to a different style; at other times, you might want to assist a somewhat misled roleplayer along a path that will make their character more enjoyable for everyone. Trying to deal with "a Wookiee role-playing as the king of Naboo" is a great example of this (thanks, Jascentia!). You might not think much of that player, but you can get the message across with words and actions appropriate for your character -- basically, feel free to react in a way that indicates that your character knows that the "king" is insane, or lying about his background. A medic might recommend a visit to the asylum, for example; others might just loudly discuss how sorry they are that the poor Wookiee's mind has gone; a grumpy miner might just make fun of his poor attempt to mimic the royal gowns; a merchant might snidely offer to assist with spending the government's budget. Overall, you should encourage the player to keep roleplaying, and help them fit their character into the world in a way that makes their RP fun for everyone (and maybe, just maybe, that insane Wookiee "king" is just what everyone needed after all...).
Although in general the Star Wars setting will make it easier to "get in character" with your language (because it is essentially like our own), one side effect of this is that it's harder to tell when someone is "out of character." In a fantasy setting, you can often recognize a fellow roleplayer immediately by their tendency to use the archaic vocabulary and emotes, but that won't happen as readily in SWG. This is a blessing and a curse -- your own roleplay immersion won't be as quickly ruined by someone else's failure to roleplay, but you might have a harder time noticing roleplaying when it's happening. This could also make it harder to promote roleplaying with newcomers -- using the archaic terms is an easy first step for the beginning roleplayer in the fantasy setting, but in Star Wars it can be a little harder to get your feet wet since the language alone won't put your mind onto the right track.
Hence, this essay. =)