Others might have had other experiences, but I haven't had great luck with leads coming straight from organic search. I know they can convert, but there'll be a lot of poor leads to wade through, and low trust even with the ones you end up working with. This industry is a little rough, since literally every single business owner I've talked to has been burned at some point, and are sick of hearing from sales men. Who's going to do a Google search looking for a random SEO company, when you're already beating off 3~5 calls a week from people trying to sell you that very service? To make things worse, local SEO is about as mysterious to most business owners as car repair is for many people who need an auto mechanic. Heavy distrust combined with ignorance of how to vet a good provider makes for nervous buyers.
Most of the business owners I've spent time with have never done a Google search looking for SEO. They've all picked from people they know, recommendations, reputation, or salesmen. If you're part of an agency, you should absolutely pursue SEO as part of your outreach strategy, but if you're a solopreneur or part of a very small team, I can't help but think your time would be much better spent speaking, teaching, writing, and finding any other way you can to be a source of useful information for your target audience.
If you're set on SEO though, start with spam hunting. Local SEO listings are almost as bad as locksmiths, and a lot of your competition could likely be knocked down a few pegs (or removed entirely) by an astute competitor.
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