Oil your flute at regular intervals, preferably monthly. Oiling will keep the wood from degrading and protect it from excess moisture. Apply 4 to 5 drops of mineral oil into the mouthpiece and allow the oil to sit for a few seconds. Pour the oil into a sink or trash can after use. Apply additional drops into the flue and swish the oil around, to ensure the interior is fully protected.
Limit the time you spend playing the flute to periods of less than 45 minutes. While it will not cause any permanent damage to play for longer periods, you risk flooding the instrument during extended periods of use. Playing the flute forces hot air and saliva through the instrument from your breath. Eventually the condensation and saliva from your breath will accumulate and begin to drip out of the flute. This is called "flooding out." Not only can this cause a gross-out factor, it also can negatively affect the tone and timbre of the instrument. Take breaks from playing every 15 to 20 minutes. "Fling" the flute dry when you notice excess moisture building up. Hold the flute firmly in one hand and make a throwing motion, without letting go of the instrument. This will force moisture to fly out of the open end of the instrument. Do this motion over a sink, ground, trash container or tub to avoid getting saliva on any clean surfaces.
Avoid eating or drinking hot liquids directly before using your flute. Food particles can enter the instrument and become rancid, leading to undesirable smells and the risk of bacterial infections. Hot liquids will heat up your breath, leading to more condensation inside the flue and a greater chance of warping the wood. Heating your flute before use on cold days will help you achieve a better tone, and reduce the chance of swelling or warping. Brushing your teeth before playing can reduce saliva production.
Dry and disinfect your flute after each use. Use a pipe-cleaner to thoroughly dry the inside of the instrument. Apply a small amount of hydrogen peroxide to a non-lint cotton wipe to disinfect the mouthpiece. Apply a small amount of hydrogen peroxide to your pipe-cleaner if you suspect a buildup of saliva or debris inside of the flute. Always store your instrument in a specially made flute case when not in use. These cases are designed to mitigate changes in humidity and temperature so that the flute does not become damaged while it is in storage.