hey,
I have been doing local seo for my own business for a while now and these are key factors that I found out to be helping a lot (i got my listing to #1 for 5-6 VERY competetive keywords)
1. Do NOT overpack your listing with Keywords, Just as humanly possible. max 2-3 keywords in the description of the listing.
2. Categories - now, this part is probably the main thing. choose the right categories that the business fits into
3. Local SEO keywords on the website content itself
4. Local Citations, websites like qype.co.uk, citywize.co.uk (i'm in UK) yellowpages etc etc help a lot
5. I found out that a listing with a radius to serve a client ranks better than just a static address, but wouldn't advice it on ur business, might be risky.
6. local seo keywords backlinks
7. fullt listing images, video
I ranked my listing in about a month time for 5-6 keywords totaling about 500k exact searches a month