The trick is to build the best vehicles for each event. If you've not built the correct vehicle, you just won't win. For sprints, pick handling and acceleration at the expense of boosts and tricks. For freestyle, go for tricks and boosts and for races, go for the middle road.
It's often best to allow the 360 to build a vehicle for you and then tweak it.
As with all racers, learn the track and get those short cuts memorised. You'll need it in the later stages.