There are always tons of Events, Gifts, Special Rewards and so on that you can collect. So make sure that you take advantage of them all and never waste any. Tap all the icons in the game that have a red dot on them. If you somehow hid the plethora of icons, tap the yellow arrows under your player photo and enjoy the goodies. There are some rewards that get refilled and can be collected multiple times per day, as well as other goodies that you can unlock while playing.