Based on your development, Animal Crossing: New Horizons assigns you a rating with a maximum rating of five-stars and here is how to achieve it.
What is your Rating?
First off you need to find out your rating but you have to wait for Isabelle to visit your island and that only happens after Tom Nook has upgraded the Residential Service tents to a full building. As soon as you have three Animal Residents, Tom Nook will work on the building and Isabelle will move into the town. You can check your rating by talking to her as she starts living in the new Residential building. She will also give you advice on how to better your rating. You can talk to her once per day so don’t forget to keep yourself updated daily.
Construction and expanding the number of people that can stay at your island is essential to your rating and so even though construction seems expensive, it has long term benefits. The new people will move into the homes that you create. A lot of incoming animals that come on random mystery tours or campsites can be invited to stay on the island. Use the amiibos card more visitors on your island.
If some of your visitors are business workers or travelling salespeople- several of them would want to set up shop on your island and that provides a huge boost to your rating. Upgrading Nook’s Cranny also helps with the rating.
Plant Trees and Flowers
Island is livelier the greener it is and New Horizon’s algorithm agrees with it. The more plants and flowers you cater to and put in the higher your rating soars. Nook’s cranny has most essential plants’ seeds and saplings. You can also visit other islands to get more variety or travel to mystery island with a Nook Miles Ticket and get a few new fruits. New flowers can be created through cross-breeding. You have to water plants every day to keep them healthy, although some villagers do lend a hand in the caring.
Do not litter or have junk and other stuff lying around, it can drastically impact your rating. Keep the island clean.
Rewards for High Score
At three stars, the island celebrates it by keeping a special ceremony and you get a visit from K.K Slider. Then you can access the island designer and terraform the island. At five stars, you get the recipe for the golden watering can and its a really nice way to highlight your journey.