Remain calm while your angel is falling. Tap precisely in the moment before hitting the bottom pipe.
Flying
Tapping too often will usually end the game prematurely. Tap only when needed, as when just about to hit the bottom pipe or quickly between pipes to gain altitude. Do not tap too much or you will hit the top pipe.
Halo
The halo is not considered part of your angel. It does not matter if it hits the pipes.