Places are still organic listings although they are not webpage results. From what I've read and what Google says on the topic, place rankings come from proximity, popularity [of the business], reviews, and depth of content for matching.
Thus what you end up with is different elements but very concepts to that of listings: the right content, the right phrase, and the right relevance. You can't guarantee these spots any more than you can other rankings and in fact I would assume proximity plays such a big factor [if I want a dry-cleaners the 5-star one 4 miles away is much less relevant than 3-star one across the street] that while you can optimize, it's only able to take you so far.
It seems like the place to start is with the updated frequency and completeness of a listing (similar to content). Insuring it's referred too in other directories also seems to help (similar to backlinks) as would keyword matching.