I say from my own personal experience that the strategy that offers the biggest return for the money invested is email marketing.
It is really easy to set up. All you need is a good email template, a way to get you new potential customers intrigued about your food specialties and a good email list. 
For the latter you’ll have to find a good email list provider, and there are lots of them on the Web some better some worse.
I, for my email marketing campaigns used email list form EmailListUS.com but you’ll have to find the on that best suits your needs.