How can I find the keywords people are using to locate a business like mine?
You can't blindly jump into an SEO strategy. You need to know what people are looking for on Google in search of businesses like yours to optimize your website for these terms.
You can do this either with Google's keyword planner or other similar tools. Download the tool and enter a term that you think people would use to find your business online. You will then be served a whole range of related keyword suggestions, including their monthly search volume.
You can then use this information to shape your strategy and understand what people are looking for.