Here's how to rank your Google My Business at the top of Google. I'm gonna show you how to optimize the whole thing, including two controversial tips that technically aren't allowed, but they work. Pick a main category that's the closest match to your top service.
If you're not sure, just check out what your top ranking competitors are using and copy that. Google shows businesses that are closest to the searcher, so you need an address in the location that you want to rank for. Set your website URL to a page that includes your main keyword, location and your business name, address and phone number.
In the business description, include keywords for your services location and anything else you want to rank for. Just make sure you keep this natural. List all of your individual services.
If you have more than one category, add each and then list the services beneath them. This one is 100% against Google's guidelines, but if they don't catch you, it makes a huge difference to your rankings. Add your main keyword to your business name like this, and if you've got dedicated pages on your website for each service, add each one as a product and include the URL here.
Most businesses do not take the time to do this, which is exactly why it works.