The three-listing map pack weighs proximity (where the searcher stands — uncontrollable), relevance (your categories and profile completeness), and prominence (reviews above all, plus overall web presence). You compete on the last two.
The controllable checklist: exact primary category, every profile field complete, photos that look current, steady review velocity with owner replies, and service pages on your site matching what you want to rank for.
Set expectations honestly: in dense markets you'll appear for searchers near you rather than city-wide — that's proximity doing its thing. The goal is winning your radius, not the whole map.