I have dozens of friends and clients who own, or work in, restaurants and bars across the country. A topic that comes up often when I talk to them is online reviews and how to best deal with them and make sure their business is presented in an accurate and positive light online.
No matter what any business owner or employee thinks of them, sites like Yelp and Trip Advisor are not going anywhere. The best way to deal with these sites is to embrace them. Acknowledge they are a part of your business and work to have a positive presence on the sites.
Mention to your most loyal customers that so many (other valuable) customers make decisions online and, if they had a couple minutes, it would mean a lot to you if they could write a brief review on one of the major online review sites. If you are doing a good job, people are happy to help.
Respond to everyone who reviews your business, positive or negative. Thank them for the visit, and their purchase, and tell them to please visit again soon. If they had an issue, address it. Explain how it was resolved and invite them back for a much better experience. Other readers will be impressed at your customer service and your hands-on approach and other reviewers will know you are paying attention. Someone is much less likely to post an inaccurate review if they know you will respond hastily.
Most importantly, keep doing a good job. If you are doing really good work, people will come back and the word will get out. If someone has a complaint about your product or service, listen to it, address it, learn from it and move on.