Is your shop planning for a bonanza?? I can probably give you a best suggestion to create a big hype about your store and also the deal that you have proposed to give for the winner. If the deal is a car, the best way to attract more number of customers to participate is by flaunting it outside your shop. Get help from a local car lifts agency or just log on to the website Asdeals.com and just send a request , so that they can get back to you.

The other best suggestion is to distribute colorful  pamphlets indicating the deal  outside the premises  of  your shop.  Follow either of what  I told you and am pretty sure your business would go great guns.