Make sure you meet all guest requirements
Each guest will have four “requirements” they have for having a good stay at your island. You can invite guests without having all four met, but you will earn less money for their stay. Instead, you want to really focus on guests for whom you meet all requirements in order to maximize your income. The four requirements include minimum lodging ratings, a certain kind of item, having caught specific critters, and for your island to have a certain vibe. For the items and vibes, these come from the type of decorations you have set up. Most decorations have qualities, like sleezy or rustic, which impact the overall vibe of the island, if you have enough. Some guests only need one or two of these items, some need the overall vibe of the island to swing a certain way.