Researched and wrote about this a few years back. Yelp's review filter algorithm is always evolving and there is A LOT of stuff they seem to take into consideration. I don't think you're going to get a solid way to guarantee the real reviews stick.
Yelp seems to consider the reviewer's overall activity/history. Seems like they look at stuff like:
IP adresses
mobile usage
connecting your Yelp account with your Facebook account
Twitter activity
having a large and active friends "base"
tag activity
"Yelp Check-Ins"
Foursquare activity (mayor)
using "public" bookmarks
how "extreme" the ratings are
"Yelp Elite" activity
a user's review frequency and location in relation to previous data
length of reviews
A LOT more
Yelp values active Yelpers. It sucks because as a business trying to get people to take the time to leave you a review can be hard enough. Now you don't know if those reviews will even make it through the review filter, and you also might need to somehow convince your customer base that they need to be active on Yelp in order for any reviews to have a better chance at sticking in the long-term:
How You Can Get Around Yelp's Pesky Review Filter
Attracting active, established Yelpers/"social media superstars" seems to be the way to go if you're trying to speed up the whole process...
Also, another tip, check out the top Yelp searches for your city. This is useful to help you determine how important an active Yelp presence might be for your industry in your city, plus you can snag the keyword information for your business descriptions etc.
Example:
Top Yelp Searches In Cleveland, OH, USA | Yelp
