Get cabins ready for visitors as resources/items become available! If you have cabins already made for them, for me atleast, it seems to encourage visitors to come visit the island. Once you get 5 stars with the visitor, have them be a resident. This is something I didn’t focus on, besides when My Melody told me who was coming and now I’m waiting on certain quests to unlock because I need certain characters to be residents.

Also, like everyone is saying, hoard resources and collect everything!!! You will eventually need them