hehe
come come my child, welcome to the world of open ended non linear games
*pats in the back*
Hehehe but seriously, the very first and most important thing in any of this kinds of games is figuring what kind of player you want to play. Is your character known for his phisical stenght or for his mental traits? Is your character strong? is he a bully or an honorable warrior? Is your character likely to use his agility to liberate objects from their money? Is your character ingelligent enough to deliber doom by reading pieces of papers and chanelling magical energies? Is your character a true diplomat able to talk anyone into slitting their own throat? Is your character one of the wisest man to ever live capable of overcoming most situations making the best choice for his pruposes violence or otherwise? Is your character a force of righteousness, a force of evil, or doesnt cares about neither? Is your character honorable? a deceiver, and outlaw, and outright criminal whatever his intentions might be? doesnt cares about either too?
A Roleplaying Game like Planescape Torment really focuses on the roleplaying part of it because is so open ended, so big, with so much to do you have to know what you want to do before you start. Most of the quest and situations oftenly have more than 1, often more than 2 and sometimes more than 3 or 4 ways to solve them. If you are roleplaying your character and limit yourself to what your character would say, you'll realize that most, if not all conversations, end up having just 1 possible solution.
Is a very different kind of game, when people says it has a great story is not because you witness it like on the FF series, is because you build it according to the actions you take in the game, you are not a memeber of the audience you are an actor. Its a very different form of game but you might learn to appreciate it and realize about the beauty of it.