Roleplaying Guide
Good roleplaying is an art, it can take years to master and some people never seem to be able to get a good grip on it. Mostly it's similar to writing fiction, the big differences are that you're writing in real time with no chance to edit, and that you're writing for the other authors.
It's impossible to learn how to RP very well from just one guide, it is an endless pursuit, and you can be sure that the best RPers get to be that way because they are constantly working on and refining their art. Those that feel their RP is already 'good enough' are doomed to never improve beyond the mediocre.
Good roleplaying breaks down to two areas, good characterization and good RP writing.
RP writing is the art of using says, emotes, descriptions etc to convey what your character is doing. This is almost exactly the same as the qualities of what makes a good fiction writer with one exception. In a story it's perfectly ok even considered normal to describe your characters emotions and thoughts, in RP it often isn't. Although there's some debate on the issue the difference comes about because when writing a novel you want people to identify with your character, when RPing you want to identify with your character, other people identify with theirs.
The other reason for this is that few people are perfect at keeping IC and OOC knowledge seperate, it's very common for someone to react differently if you emote that you fancy them, even though their character shouldn't know that and therefore shouldn't act any differently.
Generally it's better to follow the same rule that teachers of fiction writing beat their students over the head with 'show don't tell.' Don't tell people what your character is thinking or feeling, show them. Use your emotes and the way they speak to convey that they fancy that person or dislike this person.
The other keys to good RP writing are: Write something that's easy to read and flows nicely, paying attention to spelling and grammar etc as much as possible. Include all relevent details, the devil is in the details as they say and a few words to describe the way in which someone does something can add a lot to the RP. Brevity, good writing isn't longer than it has to be, the shorter your emotes and says the less work you're requiring your reader to do. Any reader would prefer a 200 page book, to a 500 page book with all the same stuff in it but 300 more pages of furniture descriptions. Speed, people don't like waiting around longer than they have to, the quicker you can RP the more RP they're getting for their time. Language, just like in fiction writing the use of certain words or phrases are much more likely to strike a chord in people and get your meaning across than others. Try to use words and phrases that create vivid imagery and convey things strongly without being overly flowery or convoluted.
Some of these do work a little at cross purposes, trying to include detail and spellcheck your RP while also trying to be quick and brief is a challenge, each person needs to strike their own balance of what works for them.
The only way to really improve your RP writing is with practice, get out their and RP and learn from others as well as seek out positive and negative critisisms. If most people think your emotes are too long and needlessly wordy maybe think about working on making them shorter. Ultimately it is up to you, but the other players are your readers, if they don't want to read your work, what is the point?
Good characterisation is the other half to good RP. It refers to being able to create a character who's interesting and realistic.
Creating an interesting character is really about creating a character that's good for the story, you might be able to make an extremely realistic tax clerk character but nobody is going to care about him. An interesting character is measured by their ability to create RP and their ability to join to and add to the RP of others.
It's important to note that RP is a collaborative effort, your character can never be the star they are one member of an ensemble cast. Sometimes the storyline might thrust you center stage but other times it might thrust someone else. People get very sick very quickly of playing with someone who tries to make all RP be about them.
A good and very common example of this is characters with traumatic pasts/lives. When a character goes through something traumatic in game, this naturally pushes them more center stage, with a lot of the RP revolving around the sympathy they get, possibly plans for revenge or ways to help them deal with it. Every other character around who has a more traumatic past steals from this attention, nobody else can ever get sympathy because what they went through is so much worse.
This doesn't mean you can't have traumatic incidents in your character's past, but it's very important for you to think about other people when you make your character, how your character can add to RP that isn't about them, and if they're likely to detract from that RP maybe you need to re-evaluate them.
Being a good side character is about both adding constructive and destcructively to RP. A character who's always nice all the time is boring, a character who's always a jerk similarly. Interesting character conflicts and situations arise from those characters who sometimes are supportive and sometimes cause conflict. If your character can do both of these, and avoid any spotlight stealing, then you probably have a really good side character.
Being a good main character is mostly about not being selfish. If the bounty hunters are after you, yes that might be your problem but if your character is really set on dealing with it all on their own it gives nobody else anything to do. When you find yourself in the spotlight is when it's more important to be gracious, involve other people in the story in important ways. In return they're more likely to do the same to you when it's their turn.
Sometimes RP isn't really about you or someone else mostly, but communal. This often happens in social RP for instance. What makes a good communal character is mostly the same things that make a good side or main character. Don't spotlight steal, get other people involved, add to the rp in interesting and not always predictable ways. Adding to the RP is important, you might think it's cool to be gruff and silent, but nobody is going to want to play with you much.
The other thing that makes a really great interesting character is the ability to make RP happen in the first place! A character with reasons to RP with a lot of people, get them involved in things, make various other types of RP happen is crucial to a fun game. Examples might be characters who throw parties, a journalist who seeks out lots of other PCs to interview etc.
If you have a character who has the qualities of both a good main character, a good side character, a good communal character, and creates RP then you have a really good interesting character!
The other half of the battle is realism.
Realism is very important and often overlooked, it doesn't matter if your character is a vampire or sorcerer. Stories must have internal validity, they must be believable within that world, even if they're fantasy stories, some would say especially if they are. The second your character starts feeling fake and not like a real person people will stop caring about them, and it's very hard to get them to again. Very good realistic characters can make people in real life cry when they're hurt, cheer when they're triumphant and swoon when they kiss, and that's what you should be aiming for.
Making a realistic character can be very hard, there's a lot of different opinions on the ways to go about it. A lot of people like to model characters on themselves or people they know very well, and this is generally a solid and reliable way to make your character quite realistic. The old writer's adage of 'write what you know'. Unfortunately it's often the case that you want to play something quite different from yourself or anybody you know. In these situations information is your friend, spend a little time on the internet researching the areas you want to look at and the people you're trying to emulate.
The more you learn the better your character is likely to be, but for most characters a few pages of wikipedia is probably sufficient. This does refer to all areas of your character, lots of people are good at doing a bit of research if they want their character to be say a doctor. But it's a lot rarer to see people do research before involving a character in a same sex relationship or making a model or muscian.
So that's characterisation, it's also largely about practice, taking critism and learning from others, but it's also very much about putting the work in before you make the character and about really being able to take a step back and thinking about the other players, who are your audience, and how you can deliver a realistic and interesting character for them.
Once you have mastered both RP writing and characterisation, the RP world will be your proverbial oyster.