Ways You Might Be Sending Your Roleplayers & RP Partners Mixed Messages

You say: "Yes, I want you in the game! Just jump right in!"
But then you: Let all of your characters ignore the new player's character, or have them give the new player's character the cold shoulder when the character tries to participate in the plot.
The message you might be sending: "You're welcome to sit down and watch me play, but I don't actually want to play with you."

How to fix this: Make an effort to get the other character really and truly involved in the game and its plot. If it happens that you have a character who isn't the friendliest, consider playing another character who can help the new character out a bit, or see if someone else's character can do it. In any case, absolutely do not let a new PC languish alone while everyone else is doing interesting and dramatic things.

You say: "Yes, I want you to join in on the plot!"
But then you: Constantly make the player's character's attempted actions fail or prove impossible, preventing the character from having any real impact on the plot/storyline; or you put your foot down on plot/storyline-affecting actions the player wants to take.
Or else you: Bring in an NPC to take care of something that the player's character wants to tackle.
Or else you: Assign the character meaningless tasks that have no real impact on the plot/storyline.
The message you might be sending: "The only role your character gets to play in the story is watch my characters do all the interesting and important things."

How to fix this: Get yourself into the habit of saying yes more often. Check out "Should I Add Or Allow This In My Game?" - if it passes, let it happen! If not, make sure the players understand your reasoning for disallowing it. Avoid creating plot-related obstacles or problems that only one character can or "should" solve - optimally, everyone should be able to take a stab at it and have a chance of making some headway on it. And remember, when it comes to fixing problems and getting things done, the PCs should always have right of way over NPCs.

You say: "Yes, you're a valuable member of the community!"
But then you: Never make an effort to involve the player in IC activity; or never engage in friendly conversation with the player OOC, even though you talk to other people OOC.
The message you might be sending: "You don't actually matter to me. In fact, I don't even like you. I just tell you this stuff out of social obligation."

How to fix this: Try to be more conscious of how much you're actually involving and interacting with your players, both IC and OOC, and how you are interacting with them. If you realize that someone might be getting left out, make an effort to change it.

You say: "Yes, you can talk to me anytime if you have an issue!"
But then you: Get snide or grouchy with players who actually do that, or blow off/shut down the discussion, or accuse them of being inconsiderate or whiny.
The message you might be sending: "...By which I mean, you can come and listen to me tell you all about how you're selfish and wrong."

How to fix this: Learn how to deal with this type of thing without being a jackass. Check out Dealing With Unhappy & Complaining Roleplayers.

You say: "I just want everyone to have fun."
But then you: Ignore or shoot down any criticism or suggestions that players have regarding the game.
Or else you: Insert elements or "twists" that completely derail or kill ongoing plots, or have your characters take actions that essentially force or lock other players out of the plot.
The message you might be sending: "I just want for me to have fun, and for everyone else to shut up and go along with whatever I want!"

How to fix this: Again, check out Dealing With Unhappy & Complaining Roleplayers. Also check out "Should I Add Or Allow This In My Game?" (And remember - just because your players aren't complaining, doesn't mean they're happy. It might just mean that they're too afraid or too demoralized to speak up.)

You say: "I want to have some plot!"
But then you: Let your character ignore anything that involves helping other characters; or ignore anything that involves doing some kind of errand/job/mission or investigation/exploration.
The message you might be sending: "I only care about the game when it's all about me."

How to fix this: First off, it almost always helps to describe a few specific elements you might like in a plot - this way, people are more likely to come up with ideas that you actually like. Secondly, try to make sure that your characters are giving other players' characters as much support as you want them to give yours. Finally, remember that plots that aren't immediately about your character can still lead to amazing character and relationship development, and can provide wonderful opportunities to reveal new things about your character.

If the problem is that your character just isn't the type to get up and go unless directly affected or confronted, then what you need is to play a more proactive character. Check out Alexis Feynman's Guide To Writing Proactive Characters and Grail Character Syndrome: How To Be The Center Of Attention And Yet Be A Total Bore for some tips.

You say: "I don't believe in forcing/pushing ships."
But then you: Have your character constantly flirt aggressively with others (even when they don't respond well), or behave in controlling/manipulative ways.
Or else you: Constantly describe how attractive your character is.
Or else you: Have NPCs comment that your and someone else's character would make a cute couple.
The message you might be sending: "Never mind what I said earlier, GIVE ME MY SHIP ALREADY!!!"

How to fix this: Refrain from engaging in the above behaviors - they make you look desperate and creepy! Take a look at So You Want To Have An Attractive Character? Also check out Reasons Your RP Characters Might Be Bad Friends Or Love Interests and Reasons Your RP Characters Might Be Creepy (In A Bad Way) for things you probably ought to avoid if you want to get a ship to sail.

You say: "I hate Mary Sues!"
But then you: Play OP characters and/or characters with excessively improbable traits.
Or else you: Always have your characters know what's going on behind everything that's happening, or make your characters always turn out to be right, or have them solve most of the problems and win most of the victories.
The message you might be sending: "...Except when I play them."

How to fix this: Give your characters more balanced and believable abilities - go here to find out how to avoid being OP, and check out Things About Skills, Talents, & Knowledge Writers Need To Know for some tips in making your character's skills and abilities believable. Also check out Building Better Backstories - Tips & Ideas and Basic Tips To Create Better Characters With Tragic & Traumatic Backstories for help in creating a more balanced backstory.

Also, make sure that everyone's characters have a fair and equal opportunity to discover things, be right, and to solve problems and kick ass. For tips on this, check out How To Roleplay Villains Fairly and Basic Tips To Create And Run A Good RP Plot.

You say: "Sure, I'll RP with you!"
But then you: Never do it. You just don't get around to it, or you've constantly got things coming up.
Or else you: Start the RP, but leave it after a few minutes.
The message you might be sending: "Actually, I don't want to RP with you, but I'm too chicken/inconsiderate to actually tell you that."

How to fix this: Start being honest, both with other players and with yourself. Ask yourself - is it really a good idea to start a new RP right now? Do you honestly have the time or energy? If not, then say as much. Do you really not want to RP with this person? Then you can say something like, "I'm sorry, but this isn't the kind of RP I'm looking for" or "I'm sorry, but our roleplaying styles don't really mesh."