Locate a private accordion instructor. Ideally, your instructor should have experience performing Mexican music. A private instructor can provide guidance that will prevent you from using a trial-and-error approach. This ensures that you progress more quickly than you would on your own, and it prevents you from developing bad habits that can be difficult to correct later.
Create a regular practice schedule. It is important to have command of fundamentals such as scales in order to successfully play any genre of music. Regular practice will make it much easier to achieve your goals on the instrument.
Listen to Mexican music that contains accordions. Immersing yourself in the genre you want to play is the best way to learn. Seek out recordings of the norteña style. You will begin to notice characteristics of the music through repeated listening.
Study sheet music collections of Mexican music for the accordion. This can be a good visual reinforcement for what you have learned from listening. It can also help you learn more songs at a faster pace.
Find other musicians to play the music with. Music should be a social activity, and creating a network of like-minded musicians will provide support and encouragement. This is when all the hours of practice will pay off with hours of enjoyment.