I will cover some very good GMB SEO tips today that will include.
How to find a competitors listing and find there registered business name to then go into the search engine of your choice preferably Google and with search operators you can then find some of the most important business citations for that competitor.
This is done by using this search operator function see below:
allintext:"businessname" + "phone number" this will bring up some omitted search results but you want to see the omitted duplicated search results for that website.