The desired finger action in flutes is quick, yet controlled, light, and relaxed. This is essential for producing smooth finger changes that are not accompanied by unwanted portamenti or clicks. When the flutes’ keys are depressed, the fingertips come to rest against the flat keys. At first, the fingers do not know the feeling of being released, so the hands clench around the body of the flute. If the fingers remain clenched, quick finger movements become difficult. Furthermore, the fingers do not begin their motion from the same position. Tense fingers may take longer to move, so the beginning of the finger motion is staggered and results in an uneven articulation. Releasing the unnecessary finger tension is the first step to an even finger technique. Relaxed fingers can react quickly and easily to the finger changes of a scale, arpeggio, or fast passage. Once the fingers are released, the fingertips learn to stay close to the keys. This is ideal because the fingers must travel a minimal distance to the keys to cover them.
Start with long tones and slow technical exercises (4 note fingerings, chromatic scale, etc) to train the fingers to do what you want. As you gain control, increase your tempo, but make sure to maintain evenness and smoothness. Articulation should be the same in all registers. Low notes should sound as sharp as high notes. Avoid playing passages quickly to prevent bad habits from developing.
Intermittent hand-to-hand coordination problems may arise in spots that involve hand crossing, finger stretching, or the like. Use the “hands alone” method to resolve issues such as a lagging right hand or left hand thumb imbalance. When hands are reunited, the emphasis moves to ensure smooth transitions between the hands with no tiny pauses where needed. Additionally, a lot of flutists recommend mirror work to encourage proper hand formation (flat wrists and naturally rounded fingers onto the keys), and eventually such corrections become habits.
For finger technique, I try to work on light, small, fast finger motions, which I hope results in clear articulation without using a lot of tongue. I use silent-key slurs for finger independence exercises and to reduce my dependency on the tongue for changing the pitch. I believe this kind of nuance of finger technique is useful for playing lyric or any modern songs requiring smooth legato. I also need to play faster with metronomes regularly to train the fingers to be evenly responsive when speed is needed. All these lead to more compact fingerings and help me play technically demanding music.
Overall, developing finger technique is like the scaffolding that all the other elements of fluting climb, in order to realize your goals. It is the building block to help you focus on phrasing, dynamics, and tone as opposed to worrying about simply producing the notes. This process of learning can be very liberating when your flute responds immediately with just a thought, much like your own fingers. When you share those little breakthroughs with other students it helps to motivate and gives new solutions to those that have hit a snag. Ideally, your finger technique leads you to where any technical challenges and details become an expression of fun, and the music springs from your soul to your audience.