Try to refrain from using shorthand. For example "Ur in 4 it now". Though it may be easier to write out, people will tend to steer clear of you and your role-play for it. If you open up a book, you won't see the author using "u" for "you". Would any respect an author for doing so otherwise, or read their book?
To type an emote in Second Life, write /me before your post. This will get rid of the semicolon (:) after your username.
Example: /me stepped into the tavern and glanced around.
In Second Life, this becomes:
Yourname stepped into the tavern and glanced around.
When your character wishes to perform an action, a good Role-Player makes sure there is a difference between actions and speech.
Roland smiled and looked over to her. "All right."
Something to avoid is using no formatting to distinguish action and speech.
Roland smiled and looked over to her. All right.
Is he saying "All right" to himself in his head or is he saying it to someone out loud? Avoid using the same format for actions as you would for speech.
When you Role-Play, try avoid making multiple short posts.
Marcus walks in.
Marcus looks about.
Marcus sees Geoffrey and walks over. "hi"
If you can, try summing it up in at least one or two posts rather than typing many small posts.
Marcus walks in and looks about. he see Geoffrey and walks over. "hi"
Better! But, it could stand to have more detail. What may people not know about his appearance that his avatar doesn't already suggest? Is he carrying anything? Any fresh scars or bruises? Don't forget to practice your grammar--get familiar with your shift key! It may not seem important, but it does make you look more skilled as a writer. Let's try something like this:
Marcus walked into the tavern and looked about with narrowed eyes. He was breathing heavier than usual, a few beads of sweat rolling down his skin. He wiped his forehead with his sleeve and tried to look calm and composed. Seeing Geoffrey, he curtly made his way over and tried to smile casually. "Hello there, friend. We need to talk."
Wow, pretty good, right? Or at least better than the first two examples! Posts like these will definitely help you get recognized in the role-play.
When a player speaks to other players in role-play, he or she should do so in a way that allows them to know that he or she is speaking out of character (OOC). The most popular way to show this is to put (( )) around what is being said. Whatever symbols you use, make sure it cannot be mistaken for In-Character role-play. For example, avoid quotations, because those are already reserved for IC speech. Be wary of using a single parenthesis or [ ] for OOC, since some use these in their In-Character posts for descriptions. Example:
Lucchino laughed and held his gut. "I love to cook!" he proclaimed. "I'm the best cook in the world! You'll find no better than me!" Lucchino even had had a certificate of culinary arts appreciation (certified by a strange dirty man in an alley and printed on the back of a restaurant's menu) and thought himself quite adept at making (burning) food. ((ack, brb, doorbell))
As mentioned in the basics, there are three no-no's in role-play.
Godmoding is the act of being all-powerful, godlike, or too perfect. With a power, magic, or ability to handle any and every situation, they become practically invincible. Nothing bad can happen to their character because the player does not allow it. In writing, this is also called a "Mary Sue"--a generally undisguised representation or proxy of the author/player within the text. Though the player may wish their character to be seen as respected, loved, and awed, because there is no conflict or realism involved, are generally seen as having a poorly developed character.
Metagaming is using knowledge gained out of character and applying it in character in a way the player's character would not have known. Example: The player is an expert in zoology, so their character is too; however, their character has never left the city or even picked up a book on animals. Example #2: Player A hears that Player B's character is going to attempt a jailbreak; Player A's character tells the warden that the prisoner is going to try and attempt an escape that night. Example #3: Somebody insulted you out of character, so now your character instantly hates their character.
Powergaming is something most of us have experienced (or perhaps done before) and is something to avoid in role-play. A powergamer tries to force moves on others, rather than attempting them. They tend to assume anything they do is successful. They always avoid hits and/or try to force their own hits on others without giving the person a chance to react, dodge, or parry. This is seen as unsporting, unsociable, and enough to ruin the fun of the other players involved. If encountered, it is best to find a way to leave the scene, or politely inform the other player of what it is they're doing.
PB&J Publishing came out with Pixar's #22 tips for writing stories, and they're definitely worth taking a look.