How Do I Get More Customers To My Deli And Catering Business. Should We Target Businesses Or Local Residents?

Hi there,
We own a small deli and would like to know how to effectively market it to bring in more catering business. We have tried mailing our $5.00 coupons via fist class mail to some business, this is working (slowly but surely), however, we would like to expand and grow our business more. We also place a small ad in the local paper every week. Would post card direct marketing be effective? Thank you kindly for your time.