chevalric, unfortunately, while there’s a ton out there for new supervisors, there’s not a lot out there for people new to our roles. That’s a big part of why I wrote this article.
One of the biggest things you can brush up on is communication skills—written and spoken. I mentioned The Sense of Style in this article, which is a great modern guide on writing, but a lot of people still turn to The Elements of Style, which a great no-nonsense (if a bit dated) guide to practical writing style. If you’re interested in what makes people tick and decide the way they do, you might also pick up Influence: The Psychology of Persuasion.
And I mentioned Jerry Weinberg in this article. His books are great for learning about the soft skills needed for computer programmers, though they can be a bit verbose at times. Good luck!