For starters,always have explicit permission before soliciting feedback via email,SMS or social.
Automating your reviews is the key to get more reviews and better ratings
If your business has an actual physical location it's a good idea to prepare sheets of paperwith a request for review.
Add a review widget to your website.On your official website or company blog,you can add a sidebar or widget which customers can click and use for posting on your business most relevant review sites.