It's far more important to cleanly override each obstacle than to go fast as you can.
Learn the courses very carefully and try to teke out a better performance on every attempt.
Downside of the game is that you'll have to buy new levels to unlovk them from the in-app purchase store.
Free money - The better you performance is the greater your rewards will be. But if you need more money, you can always go back and grind out earlier levels, or pick up some coins from the in-app purchase store. Or you can connect to the game via the Facebook icon, you'll get $200 deposited in the bank.