I have zero experience in catering or the restaurant biz but I will say this regarding Internet and social media. You want to use them all Facebook, FourSquare, Tumblr, Pinterest and every other site that comes out.
A good website will work wonders if people can find it. Regarding yelp I would ask people to post what they thought of the food/experience.
It's kind of hard to offer freebies like a restaurant when people check in (4Square) but I would tell the host if X amount of people check in to my catered event on FB or FourSquare I'll take off X%the bill.
You want people liking your biz on FB and have then tweet pictures via twitter.
I would perhaps offer a small size of your secret rub to anyone at your event that posts it on a social media site.
Also what I would do is get a smartphone and do a search for social media apps. Then install one at a time and register your biz on it.
And have those SM sites icons printed on your biz cards.
Hope this helps and best of luck!
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