what the OP is about, which seems more to be "How do you approach the role-playing aspect of the game?" rather than "What is the right way to approach the game?"
I could be wrong, though.
RC
I assume he meant the former. And with that, my ideas are:
It is good roleplaying to play your character in a way that invites other players to participate. It is bad roleplaying to play your character in a way blocks other PCs.
In terms of Improv Theatre, if you ever watch Who's Line is it Anyway, you'll notice that in all the silliness, the actors always try to get into the scene, and that whatever character is in the Lead, accepts whatever twist the other actor added.
To do otherwise is called blocking. This stops the scene from moving forward, and eliminates that actor from the scene. Not a nice or fun thing to do.
to put in RPG terms, let's say your PC has some personal matter he's handling in between dungeon crawls. He could just slink off and make the DM fork the party for him. Or, he could ask a fellow party member to accompany him, perhaps as backup or lookout. Now he's involved somebody else, making it more of a group scene.
In the same way, I consider it bad form for one player to split off from the party in the middle of the game, just to do something (like look for more treasure). What he's doing is exploiting a GM's nature to respond to player inquiry and action. He's also leaving the rest of the party when they were at a lull.
Another form of bad roleplay is to create party turmoil with statements like "That's not what my character would do" or "I'm only playing my character".
In the A-Team, BA may be afraid of flying, mostly for the purpose of creating amusing scenes to get him on the plane. But ultimately, he ends up on the plane, and he doesn't crash the campaign by killing the rest of the party when he wakes up. A bad roleplayer will use BA's fear as an excuse to not go on the quest or to start revenge killing the other players.
Yet another example of bad roleplaying is the classic Dwarf vs. Elf complex. One player will chooose a dwarf and in the campaign world backstory, determine that dwarves and elves are bitter enemies. They will then rain no end of trouble on the elf character in the party. This once again crashes the campaign as PCs start dying.
A more correct way to play this is as initial mistrust and verbal bigotry, which through many sessions turns into trust and camaradery. Well, not evey group has to end up with the dwarf and elf as bestest friends, but the gist is, they don't tear up the party over some roleplaying trait. they sling a few verbal barbs at each other, and still begrudgingly get to the work of killing monsters and taking their stuff.
Fears and biases should flavor the scene, not cause it to crash into a meaningless mess of a game.
At the end of the night, I think most players, regardless of campaign style want to have achieved lofty goals, fought challenging enemies, and found cool stuff. Having yet another session end wiith needing to make new PCs because of player infighting or rivalry gets old pretty quick.