A good way to farm is to go to the arcade and play games on the machine. The minigames are rly fun and easy, and give you tickets in return. Then you go to the front desk and convert the tickets to moonstones. The moonstones will be double the tickets! Nice outfit!
my favourite one is the astro jump and laser tag since it does give you a lot! There’s also a wheel with random awards and it can give you moonstones if you land on the star!
My grinding is only a few minutes but works like magic! 10 minutes arcade 6 minutes collecting moonstones 5 minutes working in the gas station I started with 120 moonstones Ended with 8k moonstones Started with 0 tickets Ended with 4k tickets