I recommend Letters To a Young Scientist by Edward O. Wilson even if you aren’t and don’t want to be a scientist.

Because Wilson can write. I couldn’t take advice from someone who couldn’t. His prose is that ideal combination of clarity, brevity and deep simplicity.
Because Wilson is certain that what he says is correct. Under other circumstances this might be considered arrogant, but who wants ambiguous or insecure advice?
Because Wilson’s advice is good and can be applied to a non-scientific career. For example, in the last chapter, “you will make mistakes. Try not to make big ones. Whatever the case, admit them and move on.” And rather than flocking to a path others are flocking to, “march away from the sound of the guns. Observe the fray from a distance, and while you are at it, consider making your own fray.”
My ultimate compliment to Wilson-if I had read this book when I was considering careers, I might well have become a scientist.