For years I tried a variety of methods, straight xp for monsters, time-based, etc. but nothing really encouraged role-playing that much. I then began a tedious process of giving players +/- ticks for roleplaying as the game progressed and it helped out quite a bit. (When I say roleplaying, part of what I mean is playing your character as you say he is.)
IIRC, this resulted in some players gaining bonuses of as much as 50% of their base experience but usually around 10-20% (and in some cases -20%). So while a PC who did the minimum roleplaying would get 1000xp, a good player might get as much as 1500xp.
IIRC, this resulted in some players gaining bonuses of as much as 50% of their base experience but usually around 10-20% (and in some cases -20%). So while a PC who did the minimum roleplaying would get 1000xp, a good player might get as much as 1500xp.