You will get a coin multiplier for collecting a lot of coins in a row. The longer you can maintain your streak, the higher the multiplier will increase. It is somewhat difficult to get it past X2. In order to do so, you must collect coins very quickly. After a row of coins has finished, get to the next as fast as possible. You only have about two seconds before the multiplier starts to decay, at which point filling it up again will only reset the multiplier at its current level. Save your coins to buy new cars instead of spending them on upgrading temporary power ups.
Free bonuses
You will sometimes be given an option to watch an advertisement video to give yourself a boost. This can happen after you crash or reach at the end of a level. Agree to watch the video, and when it appears, select the "X" button at the top right corner. This will close the advertisement, but you will still get the bonus. Do this at every opportunity, especially at the end of a level where you can double your total coins. Note: Some ads will play automatically.
Lottery tickets
Lottery tickets can be found in certain levels. When collected, you will have a chance of getting boosts as a reward. They have a golden aura around them allowing them to be found easily. They may appear between cars and other hard-to-reach places.
Quick drop
Swipe up to jump, then swipe down while in mid-air to bring your car back down faster. This is useful during bad jumps and dealing with hazards.