I think you should first create google business profiles in your target locations, I know some business have "virtually addresses" or virtual offices just to create their local google business profile, proximity is the biggest factor in map results, and if you dont have a google business profile in your target area, its very unlikely that your website/business will show up in the map pack.

After that , as @designmediaUSA has suggested, just research how your competitors are doing and try to copy their strategy, You can check what are the top business in a specific area for your keyword using https://www.gmbradar.com/, It will show rankings of your business and also your top competitors, analyze your top competitors and create a local SEO strategy accordingly, I think it will give you a good starting point..