Best way I've learned is like others have said..to immerse yourself. When I first went to Jamaica, I hardly knew anything as far as what they were saying. I made friends, spent more time listening to the music, immersed myself in everything Jamaican. Plus I had some friends who were in the country in JA, and had super thick accents so I kinda had to learn if I wanted to have more than a thirty second phone call consisting of " huh"??? LOL!
Now I can understand most things, I can type a fair bit of it...and can speak a little very terribly!!
You can't really be "taught" patois....I've seen people type the same sentance thirty different ways...it's kinda one of those things you just have to learn through being around it!