Casting a shadow on your model can give very nice and cool look. But it might not be as easy as you think.
If you are usein snoot to cast a shadow then to get nice sharp edge on your shadow, you will need to get model as close as possible to your shadow caster. But take your snoot far from model so you can get larger area.
If you have a projector then its is easyer for you, and that is the best solution.