Build communities for your population on the island. Basically farms (this will help you complete also the tablet of planting every crop) and have farmers work on them, houses with beds, community toilets and baths, and a big kitchen with a big eating room besides it (basically a restaurant).What's the best way to earn hearts on the IoA? I have 800, and I need 7,500 to unlock the last three islands on the map. I have beaten the game already.
This will give you tons of hearts each day. If you want to seriously build in the future, just transport everyone to one area, and build the community there, and make that community really fast, with no intent of making it good look or anything, as you will tear it down when you actually want to build whatever you want in the island.
I know theres also an explorer island with some metal slimes that run super fast (dont remember which island they are in), if you befriend one of those, every day you can persue it (in the area of the islalnd of awakening you put it in) to get 100 hearts.
No problem, hope it helps! :D