You can earn coins by
- completing match-3 levels,
- reading newspapers,
- collecting tips on the tables,
- completing Collect Earnings tasks,
- sending lives to your Club friends,
- when you successfully complete a Club Race,
- playing Special Levels.
You also earn coins when you login with Facebook for the first time and join the Clubs the first time. You can also get coins from the Daily Gifts.
Coins will be useful in purchasing power-ups, boosters, and extra moves. You can also use them to fill your lives once you run out of them.