Touch ID is so very convenient, allowing you to keep your phone secure while eliminating the need to enter your passcode every time you unlock your iPhone. And because you don't need to enter your passcode every time, you can use a longer, more secure passcode without any extra hassle, thus increasing your iPhone's security as well.
Touch ID is so convenient. Except when it isn't.
Because there are always those times when it just won't read your fingerprint, no matter what position your finger is in; and after multiple failed tries you are forced to enter a passcode to unlock the phone. If you have an extra-secure passcode, the inconvenience is multiplied.
At least, this was my experience until our CEO David Averbach showed me this cool trick that resulted in Touch ID working for me every time:
Go to Settings>touch ID & Passcode and enter your passcode.
Place one of the fingers for which you have Touch ID enabled on the home button. If you are using Finger 2, then Finger 2 should turn gray. Lift and place your finger on the Home button in a slightly different position until Finger 2 turns gray.
Repeat this, changing position slightly each time, until you have entered a whole range of positions.
Do this for each of the fingers you use for Touch ID.
From now on, your Touch ID should be very responsive. These days if I press my Home button to wake up my iPhone and then just rest my finger for a brief moment, that is usually all it takes to unlock my iPhone.