Tip: Improve Touch ID Accuracy
Andy Ihnatko had a tip on MacBreak Weekly 600 about fixing inaccuracies with Touch ID on iPhones. If you're suddenly having problems getting Touch ID to recognize your finger, go into Settings > Touch ID & Passcode, delete that fingerprint, and re-enroll it. You can hold your finger on the home button to see which fingerprint it corresponds to as well.
Touch ID is supposed to deal with changes to your fingerprint over time to some extent, but sometimes things can change enough where it doesn't recognize it as often anymore. It might even make a difference if you had trained your finger in the spring or summer and have been trying to use it in the winter when your skin is much more dry. Often times just going through that initial setup process again with your fingerprint will improve the accuracy significantly.