The key is patience, diligence, and active efforts to understand what is going on. This sometimes requires research. There are numerous great scholars who have devoted years of their lives to the study of Moby Dick and Melville's other writings. There are also numerous websites along the lines of Sparksnotes that can help you...but if you want to dig deep and learn deep you need to search for the mine with the most gold--and that is in the land of the scholars!
Here are some links to help you get started: