Working hard is definitely the lesson that taught me the most. When I started printing years ago I was often happy after one or two sheets of simple testing. Today it takes a fair bit more effort to get me to a point where I'm satisfied with a print, and often I spend three or four sheets of paper before I end up in a place where I start to like what I see.
Patience is also a virtue in the darkroom. You can't rush perfection. Think of each individual print as if it was the last one you were ever going to make. Spend time with the negative, make some work prints and study them closely. Take notes, careful ones, that tell you later exactly what you did. This not only helps you learn, but it also helps you remember.
Try one technique at a time. Dodging and burning is essential, and learning how to make a good negative is imperative. Split grade printing is a good tool, but it's best to learn basics first.