It was a great step in science when men became convinced that, in order to understand the nature of things, they must begin by asking, not whether a thing is good or bad, noxious or beneficial, but of what kind it is? And how much is there of it? Quality and Quantity were then first recognised as the primary features to be observed in scientific inquiry.
The number one piece of advice I would share is to recruit a mentor. Find someone you admire who is at least one generation older, and has no direct authority over you. Lack of context and perspective can cost you months and years--with a bad career choice, an unwise relocation, short-term negotiating posture, and, generally speaking, sophomoric thinking.