Benefits
Consistent fingering and arm form are necessary for playing well. Fingering will vary based on notes of the music, but some guidelines are useful to determine the best fingering for you.
The following link is a good place to start. Determining which fingers to use is a purposeful, problem-solving activity requiring musical analysis and trial and error.
https://www.key-notes.com/blog/piano-fingering
Guidelines for the Right Hand
Arm form begins at the shoulder and ends at the ends of the fingers directly over the buttons. The fingering motion is directly down and up. This position requires that the elbow be forward with the wrist, hand, and fingers in a relaxed, natural arc.
Play each different button with a different digit (thumb and four fingers). Maintain a steady hand position with fingers positioned over the notes. In this way a specific note is a specific finger. The lower notes are under the lower fingers, and the higher notes are under the higher fingers.
As you scan ahead on the music, you see notes that are higher or lower than your current position. So you have to transition the position of the right hand and fingers.
Transition the hand using a reference button. For example, replace a current finger on a button with a different finger. Shift the remaining fingers to the new notes. Play the notes, then shift the hand again using a reference button.
Consider adjusting the wrist and hand angle up or down the keyboard to better fit the selection of buttons. Consider alternate fingerings and buttons in other rows. Consider using some awkward positions to get to a good position for a particular section of music.
Mark fingerings in the music and play them consistently. If you discover a better fingering, update your finger markings.
The goal is to play in a relaxed and confident manner without thinking of fingering.
The Practice
http://knopaccordeon.ggms.nl/bladmuzieke.html
