For new players id suggest focusing on Infinite Illusion as it will probably be the thing that gets you the most coupons.

To do this you'll need to:

-Have a decent level

-Know what teams work for each stage

-Max out your ninjas to your lvl (Optional early game but for better result i'd suggest it)

I started my 6th alt and grinded levels and made a team with a decent chase and mystery damage, and I get around 900 coupons a week just from this. Not mentioning the lucky wheel, month attendance, Tree and events which would normally let me gather around 1,000-1,200 coupons a week.