Reading accordion music requires a good overall understanding of musical notation. Accordion sheet music is a more specialized form of sheet music than more mainstream musical instruments like trumpet or clarinet. The various styles of accordions share the same basic sheet music except for the more exotic varieties of accordion which have instrument-specific notations.
Study the musical notations of instrumental sheet music. Accordion sheet music is written on a standard musical staff with the same standard note structure as piano music.
Learn the chromatic scale. Many accordions are of the diatonic button style and the buttons on the melody side of the keyboard are arranged according to to the chromatic scale.
Move up the chord buttons in fifths, in ascending order, and back down again in fourths, in descending order. The chord buttons let an accordionist play chords while playing both the bass line and the treble line. The chords are most often written in bold print on accordion music.
Note the accordion music's placement of "bellow-shakes," accents played by literally shaking the bellows to add a touch of vibrato to accordion playing. Many experienced accordion players know instinctively when to shake the bellows to provide the right tone, while beginners and less experienced players can add them to the sheet music themselves.
Modify the accordion music for the concertina style of accordion. Transpose the notes in chords which are normally played with a button. Concertina players can also easily use violin music for the melody lines as the legato playing style of the concertina lends itself well to violin music.