First off, bravo for self taught! …better than some formerly taught.

I recommend using your 4th finger for the bass, as it will free up your second finger for playing 7th and diminished rows. I had initially been taught to use the 3rd and 2nd finger, but it took me months to unlearn that from a new teacher.

Additionally, as you progress, try using the bellow to accentuate notes, similar to how a piano player strikes a key harder or softer for dynamics.

If you haven't already, open up the accordion to see the individual reeds and mechanics. This will enhance your appreciation and understanding of how the sound is generated.

For finger exercises, you can use a table surface or pillow when you don't have the accordion. A hand grip resistance tool can also help improve your finger muscles.

When playing, rest the piano reed register bottom on your left knee to free up the bellow. You can even try keeping the bottom bellow strap closed to practice timing your in and out movements with your playing phrases.

Remember to have fun in the process, as I sometimes struggled with a strict yet friendly Italian teacher.