Earn Coins Easily
A good way to earn coins is to visit neighbors and feed their animals. For example, if you purchase an apple for 5 coins and then go to a neighbor's and feed it to their pet, you will be rewarded with 17 coins.
Also, plant fruit trees. While these seem expensive at first, you will earn the money back very rapidly from selling the fruit on.
Do all of the races (10) that are available each day.