The best way to earn more Coins is by winning matches.
Every time you enter a match you will pay an entry fee. Win the match and you will win your stake back as well as your opponents! Move up the tours and you could win prizes of 20 million Coins!
You can also earn Coins by opening Chests and you will receive a free Chest every 4 hours.
Check out the "What are Chests?" section for more information about Chests.