Ever since I started using Google Maps, there was a lack of local establishments for the local business in my community. I was very frustrated for not being able to locate the local businesses in the maps and hence was unable to guide any one using the Google Maps. That time I realized, for my community where people mostly recognize the local business and where house / plot / home addresses are not accurate or not present, these establishments are the most important for my city/country.
So, for the period of over 10 years, I can now see local guides including me have not not only added lots of businesses but also reviewed. People are now being helped out by using reviews, their menu photos, and every little info for that local business.
For local business point of view, it is the important thing if they are recognized. So, I always try to post their establishment photo as well if required, their timings and the services/goods they offer. Some local business when they maps themselves, they often put their wrong address. While reviewing, we always look at the addresses and try to fix them as possible, otherwise we all know that would be a problem for user search. Reviewers should also look for the improper photo that may disturb the user search, so they should flag irrelevant photos uploaded by the other users and make sure they post the most relevant photo. For a restaurant, I always try to at least their Menu card first so that their menu, delivery and contact details should be shown (this is quite relevant for my city at least).
School/institution campuses is the thing I care about. Their multiple campuses often confuses by not having proper addresses or label for the campus number or name. In my city, there are lots of school systems running their many branches in almost all of the neighbor hood. Because of their same name, Google maps often consider them as duplicate, so I always make sure to add the campus tag in the main label.
Language is also an important thing. For local business, I always try to put local names as well for the people who do not understand the English. This is quite interesting thing. Usually we do not care about the local language name in the local businesses, but the local language names are heavily used by the people.
Local business establishment should be carefully added since they are the points people search the most.