Ask HN: How to hack Yelp?

I've been helping family members with their small business websites, and they keep asking about their Yelp ratings. I know exactly what to do to help boost Google ratings (add meta descriptions, alt text, etc), but I have no clue about Yelp and there don't seem to be that many articles about it. I was hoping to get some advice from the HN community. What does the $300 a month in advertising get you? Does paying Yelp to advertise give you more control over your listing? Or are advertisers given favorable treatment from customer support, etc? Why are good, organic reviews deleted? How can you remove/unpromote unfair reviews? I understand that Yelp has to protect this information, the same way Google does, but at least Google has instructions about how to be a "good" website, where I'm totally at a loss for Yelp. Thanks for your help, Kevin