Tips To Be A More Thoughtful & Considerate Roleplayer
A huge part of being a good roleplayer is being thoughtful and considerate toward others - almost nobody wants to play with somebody who is selfish, lazy, or controlling where the game is concerned. So here are some ways you can be more mindful of the needs, wants, and feelings of other players.
Remember that what the other players want matters as much as what you want. And you need to be willing to discuss what you want and come to a compromise. Remember, most people don't want play for your characters - they want to play with them. They should be playing with you because it's fun for them, not just to give you an experience that you want. If you have a lot of very exacting wants or need everything in your roleplay to be just so, you should look into writing fiction instead.
Acknowledge and respect that different people have different playstyles, and that's okay. If you and another player can't come to a compromise, it doesn't necessarily mean that the other player is a "bad" roleplayer - it might just be that you have mutually incompatible playstyles and you just aren't good fits for each other.
Whatever you're planning, ask yourself if there's anything in it for other people's characters. Will it give them a sense of meaningful accomplishment that isn't just about helping your character? Will it help them achieve any personal goals in an interesting and satisfying manner? Will it help them grow and develop as people? Will it give them something new and interesting to explore? Will it involve anything they/their characters already care about? These kinds of things can get people hooked and invested. On the other hands, RP plots that are based mainly around fulfilling your own characters' needs, wants, and dreams or that are primarily focused on making your own character achieve greatness grow tiresome very quickly.
Don't expect other players' characters to do anything for your characters that you wouldn't be willing to to have yours do for them. If you expect their characters to offer yours emotional support, then be willing to have yours do the same for their characters at some point. If you expect their characters to help yours achieve a goal, then be willing to return the favor.
Make sure other players' characters get opportunity to be in the spotlight. Did a plotline where your character was at the center of things just finish? Then don't jump in to start up another one - give other people the chance to do something. Likewise, did your character just solve some big problem recently? When the next one pops up, hang back a little and give others the chance to try. Everyone wants to do something that matters; if there's nothing meaningful for them to accomplish, they have no reason to play.
Take some creative responsibility. Make some effort to come up with ideas for the story or setting. Describe stuff that would logically be under your creative jurisdiction - like your characters' homes or rooms - especially if other people's characters are explicitly looking at them.
If you're planning to throw in something big, ask what others think of it first. If you're considering throwing in something that would be big enough to change the status quo in a major way (EG, destroying the characters' hangout, forcing them to go on the run, or capturing them and taking them someplace else) or doing anything that would reasonably demand their full and immediate attention, ask what they think of it first.
Ask if there's anything that might make the other players uncomfortable if there are good odds the RP might go into often-uncomfortable territory. If you're not sure whether people will be all right with something, ask. As a general rule, subject matter to be cautious about includes violence, abuse, gore, compulsive behaviors, and sex - particularly if graphically depicted or intimately detailed.
Give players options at critical points that you have control over. If the plot reaches a point where you have a number of possible routes you could take with each one having different consequences that would affect other people's characters in a big way, ask them which direction they'd like to go in. A good way to do this is to make a few suggestions while giving them the option to make their own suggestions if they want.
Give a hand to players who seem to be having trouble. If players seem confused or unsure of what to do, ask if there's anything you could help them with. If their characters don't seem to be doing much, have your character or characters go and interact with them.
Watch out for signs that other players are stressed, frustrated, or bored. Signs of this can include being unusually rude or short tempered OOC, a long string of unusually-short IC posts, few to no posts at all, or their characters acting unusually sad, angry, aggressive, rude, or irritable for no apparent reason. If you notice this kind of thing in another player, you might ask something along the lines of, "Is everything okay? Are you bored or is there something going on?" If the player is stressed, let the player know it's okay to take a break for awhile. If possible (you don't have to do it if you're not up to it!), you might also offer to listen to the player's troubles or offer to just talk about something else for awhile. If the player is bored or frustrated with the game, see if you can work together to come up with some things to make it more fun.
Take care of yourself. This is one that far, far too many players overlook. If you're stressed out to the point where it's hard to be patient with other players, you're not going to be a very pleasant person to play with. There's no shame in taking a break from the game while you pull yourself back together or deal with your other problems. And if a player stresses you out by constantly dumping troubles on you, you are well within your rights to set boundaries and limits on that. And of course, taking care of yourself includes standing up for yourself when you encounter a parasitic roleplayer.
If you have to drop out or quit, say something. Don't just ghost on your players - if you have to drop the RP for any reason, let them know that you have to leave - and whether it's going to be temporary, permanent, or if you're not sure which. If you're in a group RP, work out how the players will handle the absence of your character. (Should they find a new player for your character? Act as if your character is on vacation? Dead?) In any case, just leaving without saying a word can often leave players unsure of how to continue on in the game, make them worry that something happened to you, or leave them anxious that they've done something to hurt or seriously bother you.
Other pages you should look at:
Beginner Tips For Entering A Roleplaying Community
Right & Wrong Questions To Ask A Roleplaying Community
Starting & Running Roleplays & Bringing In New Players
When A Game Master Or Roleplay Admin Might Be Power-Tripping - And What To Do About It
The RP Character Playability Test
General Roleplaying Tips & Advice
Common Problems In Roleplaying Characters
Common Game-Ruining Mistakes Roleplayers Make
Dealing With Unhappy & Complaining Roleplayers