Grind the repayable exhibition events (and when available, the Daily Gauntlet).
Start maximizing your customizations by purchasing one in each of the four categories. They will allow you to get extra money every race, no matter if you win or lose. These earnings will help upgrade your bike faster.
Perfect start
Tap the "Start" icon just as the fourth light turns green.
Restore energy and fuel
Advance the time on your device by an hour to get a chance to race again. Then, set the time back to its correct value.
Upgrades
Start by upgrading your engine with extra power, then complete all the tier upgrades before moving to a new stage. Upgrade your bike evenly to keep it at top performance.