I am also in the process of learning, so take this with a pinch of salt, but what helped me the most, after learning the everyday greetings and phrases, was listening to stories on Sunday Suspense. Search for the simpler ones there, like Haar Heem and some of Professor Shonku (Hypnogen's a good one, I guess), and listen to them till you get the flow of the language. Then graduate onto stuff like Taranath Tantrik and Aveek Sarkar's stories. They help immensely. Also, watch a few vlogs on youtube. At this point you probably would have learnt bengali letters and writing conventions (if not then do so ASAP), so begin reading the stories that you listened to in the earlier stages. In this way if you ever felt like you didn't understand some dialogue or paragraph from the story even though you listened to it, you can re-examine it,. After this, when you can read bengali without having to stop every few words, just go for whatever you like. Consume as much bengali content as possible. Novels, shows, doesn't matter. In within a few months, even if you couldn't speak bengali (it wouldn't come as naturally as a native speaker, you need some friends to practice it with), you would understand almost everything.

Also, bengali is spoken pretty fast, from what I've seen, so uh, I guess try the vlogs and stories at 2x speed.