It helps if you speak French. Also travelling often to Haiti, reading newspaper, listening to music. It's a very basic language, not that hard to master. However native French speaker always tend to make it sound more French, as it seems more logical.
I observed the pronunciation is easier for Anglo-Saxons than regular French. Once you are back in the DR, make sure to establish friendship with Haitians, and tell them you want to practice your Creole. You can speak Creole everyday here, and sometimes more Creole than Spanish depending on your whereabouts...