So you want to start a local SEO business?
I ran an SEO business Online Media Masters for 4 years and mainly focused on helping clients rank higher in Google Maps.
I would help them with SEO audits, citations (core online profiles/directories), on-page SEO, speed optimization and Google Search Console. In 3 months my website was getting around 500 visitors/day resulting in about 2 inquiries/day for my services. This was on top of the $600/month affiliate income through my blog.