Tips and Tricks
Restart Races to Save Fuel
When you finish a race and discover that you didn't meet a goal (for example, you might be called upon to complete a certain number of flips and come up short), you'll have to spend more precious fuel if you want to make another attempt. However, there's no such penalty if partway through the race, you give up because it's obvious you're not going to meet your goal. Definitely pay attention to such things, and don't be afraid to restart a race if you're coming up short. It's better than having to wait for more fuel.
Find Parts When Upgrading
Upgrades to your bike are sometimes quite costly, but you can make them less expensive by finding certain parts before you take the plunge. When you look around the map and consider the races you accept, you can preview the potential rewards ahead of time. Choose the missions where there is a chance that you'll spin the wheel and earn discounts, or you'll wind up spending a lot more than you have to!
General Game Tips
The better you do in a race, the more coins you earn.
When the town's resident fanboy asks you to perform flips, you need to be careful about your count. If you do a flip but wipe out before you hit the next checkpoint, that flip won't be added to your total.
When you select a level on the world map, you can check the right-hand menu to see what parts can be found within. You can't actually find the parts in the level, however. You simply get a chance to spin the Parts Wheel after you've successfully completed the stage.
Certain parts make certain bike upgrades much cheaper, so race for them when possible! You can upgrade without parts, but doing so costs tons of coins.
Lean into climbs to take them without sliding backwards.
Leaning backwards while descending helps you keep your balance on perilous slopes.
Got thing to keep in mind is that restarting a race doesn't cost any! This is an important point to remember when a quest requires you to perform a certain number of stunts. If you don't think you're going to make it, just restart before hitting the finish line.