Get back to your customers right away. If there is an issue, you have a chance to fix it before they publish a negative review online.
A lot of your customers probably had a good experience with your business. However, many don't think about writing anything online. Asking them politely how they felt about the service may remind them to write something about you.
There are many major directories across the web where customers rate your business with the star system. Talke control of your information across the highest traffic sites.