Swiping down causes the player to slide. Can be used to go under low objects as well as tackle other runners.
Slide into as many objects as you can, as this will significantly increase your Star store count.
Swiping down in mid air will bring you back to Earth much faster than just landing regularly.
Having trouble beating your friend's score? Try spending some gems on boosts at the start of a round and upgrading their effectiveness as well.
Need more gems for boosts? Finishing Collectible Tile Words are a good constant source of funds. Otherwise, check how far away you are from leveling up. The gem rewards for gaining a new level are hefty.
If you're using one or more star multiplier boosts, make sure you collect as many stars as possible during your turn. Smashing into wooden breakables and completing star combos will help you there as well as the trusty star magnet pickup.
Remember that you can lane switch in midair. This is very useful to jump from rafter to rafter avoiding heavy traffic below.