Fuel
Fuel is required to access the arena. Because it serves as the game's energy system, you must also conserve it and spend it wisely. Use the arena for grinding and farming before going to more advanced campaign rounds.
Missiles
When you have a missile on your tail begin using the "Evade" button or you can steer back and forth or up and down to avoid impact. If you have an upgraded machine gun, aim at the enemy's fuselage. It is usually better to avoid and defend your plane instead of attacking.
Upgrades
Spend coins to upgrade your gun's damage and cool down rate as you continue making progress. Upgrade your hanger to boost your plane's speed. However, having too much speed will also decrease ability your control your plane.