I think @Three-Eyed-Crow hit something important, too. It always helps to incorporate the other players into your interests. A player can tell when someone doesn't give a shit about them in favor of meeting their RP needs. Players who tend to ignore other people's poses or follow the flow of a scene tend to make others feel like they're really just roleplaying around someone, rather than with them. It's very important to gauge how active or passive you intend to be in a scene, and to always remember to share the stage.
Another point? It's sometimes very hard to incorporate new players into RP when their character designs don't fit the feel of emotional gravitas of a scene/game. A bubbly, pacifist cartoon fan who fails to notice there's even a war going on, on a genocidal Battlestar game, might leave players feeling like they're being distracted from the energy they're trying to capture in a scene.
So before you chargen a character who has no interest in dramatic scenes, combat, roleplaying around sad characters, or wanting to follow military protocol might not be the right fit for the game, and that's not anyone else on the game's fault that it doesn't mix. You have got to ask yourself, during cgen, how the character will fit. It's for your own good.