And then you must pin it a some points to your character. Probably you also need to set up a bit of an animation of your character to get some more dynamics in your cloth. A draping will only apply gravity, just a small movement of the character (for instance a hand, arm or leg) will generate a few ripples. Just remember that the animation doesn't have to be realistic as long as the result looks good. Don't forget to set up the proper collision objects.

As far as a primitive goes, even the clothplane is too limited in polygons. There are plenty better sheets available (for free), you want as many polygons as possible. First let the sheet (of the desired size) fall over a cube (sized about a quarter of the sheet) and see if you like the resulting folds. Play with the cloth settings until you find the type of cloth you think is fitting your scene (so decide if it is a silk or leather sheet).