In Animal Crossing: New Horizons you can customize your island in a number of ways. You can decorate it as you like in any style you want. While you are decorating your island, you can get a note from Isabelle. As your island rating changes, more residents will appear as KK Slider and new items and features will become available.
Raising the rating of your island is a fairly straightforward but very cranky process. You can increase the rating of your island by attracting residents and beautifying your island with decorations like flowers, fences, and trees. Pulling out weeds can also help increase your island's rating. Before you can get a three-star rating, you must first pass the two-star rating. To get a two-star rating, you must attract eight residents. To do this, unlock the museum, Nook's Cranny, and complete tasks for Tom Nook, like building the bridge and placing new plots of land.
Once you get two stars, getting up to three stars gets a bit more cranky and requires more work to beautify the island. At this time, there is no known exact way to increase your rating. So far, it seems the best way to categorize the island is to simply drop large amounts of decorations. We have found that fences, flowers, and craftables work well, and some of the more expensive items can have a bigger effect on the bill. It looks like you can achieve the three star rating by placing around 50 craft decorations, 50 fences, and over 100 flowers while still maintaining the eight residents needed for a two star rating.
While that sounds like a lot of work, you can place these items anywhere you like. You can throw all the decorations around the island at random or you can use them to spruce up your island however you want. Decorations like plants and crafts are quite broad categories and can go a long way in making your island beautiful.
