On starting note there probably better methods for creating deep characters. Nothing beats just thoroughly preparing to acting out your character. However I’d like to share something that works for me fairly well, is easy and provides good results.
One of the easiest way to play a character to pick an archetype and stick to it. A Grizzled Veteran. A Shy Bookworm Mage. Greedy Thief. These simple concepts are totally playable, however you will either bore quickly with how basic your character are or you will have problems in places where your character behavior is undefined. How does Lone Gunman behave when terrified? How will behave your Enigmatic Mage, when confronted in prolonged social scenario he cannot retreat from?
There are two steps that I take over this basic method:
1. Pick another archetype. Instead of acting upon one stereotype, pick two of them. For once if the given scene does not fit your archetype, perhaps it will for the other one. Maybe your Grizzled Veteran is also a Hardworking Craftsman. Even if in investigation a Veteran might not have a lot of to say, as a Craftsman you could make some points in clues related to your expertise. Your Bookworm Mage could also be… a Berserker. In violent, critical situation you can show how your mystical character break and resort to violence.
Secondly this gives others an impression of depth. Those are still simple concepts, but when switching between them shows that character is complex. It can resort to multiple solutions to obstacles it encounter. In addition it gives you an opportunity to invent an interesting character history.
2. Prepare for uneasy situations. Like mentioned before – sometimes when creating your character you were prepared for entirely different sessions. Now during whole session of interrogating witnesses and gathering clues you have no idea how to acts with your Gloomy Assassin. The remedy is simple – be prepared for situations that are hardest and not well defined for your archetype. Whenever I create a character I prepare for whole range of situations. Even writing a one throwaway line to use during session will be useful. My list contains:
Trying to Inspire