Doing this by yourself is pretty much impossible, since you can't make your character come up with ideas you didn't come up with yourself. In my experience, it worked quite well to rely on a little subtle help from the Game Master or hints from your group of players. Unfortunately, these little "out of game" moments might annoy you if you'd rather maintain the atmosphere.

In my case, I played a wizard of sorts. (I'm from Germany, where we have our own D&D ripoff named *Das Schwarze Auge* ["the black eye"]) and he's able to make prophecies. The game master can slip him hints every once in a while, which makes my character able to come up with ideas I wouldn't have thought of all by myself.