At this point I don't have too many tips on learning the bandoneón, but as I learn I will share any little gems I have here in hopes that they may help others learn faster. I'm sure some will seem obvious, but still having someone tell me has helped me along the way.

Tip 1: Scales

Learning to play all of your major, minor (at least harmonic minor) scales and major, minor, dominant, and diminished arpeggios with both hands, striking the keys with weight in your fingers, slightly separated notes, and with constant airflow, will be the most useful 1000+ hours you will spend with your instrument. Its painful, it will give you headache, you'll wonder why you even decided to play the bandoneón but do it anyway and you will see tremendous results (and eventually you will understand why... but don't expect to understand in the first week, or month....).