1. By doing all the quests you can for the day i.e. Food, Squishy, Weapon, Toy, Clothes, Book.
2. Spend some time buying everything you can from the NPC shops related to those quests.
3. Filling creatu collections or the regular collections can get you there really quick!
4. If you can play kir's quest or K1R807 quest, that will help as well
5. Visiting the Guardian shrines and turning in stuff - but this will take awhile
There are lots of different ways to do it! The first two seem to be the most consistent, because once you stock up on all the items you can, you'll have a much easier time with it.