You can earn Coins from Bonus Words. These are the words which you have created that are not in the crossword. To check your Bonus Words, tap the Star icon on the lower left side of the game screen.

You may also watch a free Video Ad to earn Coins. To do this, tap the Play button icon in the lower-left corner of the main menu.

Tap the 'Yes' button and watch the video until the end to claim your rewards.