Coins
When in free flight, collect all the coins in a trail to earn a perfect bonus, which rewards you with five extra coins.
Restoring energy
When running out of energy and there are no hearts within sight, fly as high as possible to start gliding. Even when totally out of energy, you can still glide downward and hopefully get enough time to find another heart. Male sure to angle yourself downward when you are out of energy to avoid plummeting to the ground.
Upgrades
Spend coins to upgrade Frankie, your starting character because it will be awhile before you can unlock an additional character. You can improve his Speed, Energy, Turning, and Magnet. Speed allows Frankie to fly faster. Energy increases his available energy. Turning allows his movements to be sharper. Magnet affects the magnet power-up. Focus on Energy and Speed at first, followed by Turning. Because the Magnet is situational, you can upgrade that last.