Breeding
Continuously breed horses to increase the chance of getting a new breed. You can purchase new horses from the Marketplace for coins or visit your neighbors, tap their horses, and use them for breeding.
Food
Horses must be fed often and require a lot of food. Keep your farms producing some extra crops. Balance your crops in order to produce the most advanced ones. If you have too many and your barn gets full, sell them for a small profit.
Mini-games
When you horse has a need, you will have to play a mini-game to care for them. This is how they are level up, become adults, and develop into better horses with more energy for racing. Each time a horse's need is tended to, the horse will gain extra energy. It is best to do this after a race to avoid wasting that earned energy.