My career got started with a job in tech support. Some of the most important lessons I learned came from books my supervisor shared. Here are a few that turned out to be pivotal and timeless.
QBQ! The Question Behind the Question is a concise description of the kinds of questions that lead away from blame and procrastination, toward problem solving and personal accountability. Questions like "what can I do to solve this?" or "how can I adapt to this situation?" It proved to be a very useful habit of thought for tech-support, because direct service and problem solving are the key performance issues in that job.
Time Management for Systems Administrators, based heavily on Getting Things Done, was a huge win. It describes exactly how to prioritize tasks to manage urgent work promptly, and keep momentum on non-urgent but important activities related to growth and regular maintenance. It also covers the basics of goal-setting, avoiding things that should not be done at all, and of course, dealing with interruptions. It remains the most practical time management approach I've seen to date.
The 7 Habits of Highly Effective People delivers exactly as the title suggests. Be Proactive, begin with the end in mind, and put first things first are essential principles to achieving goals. Paired with sharpen the saw and you've got a recipe for a lifetime of growth. Underrated, though, is seek first to understand, then to be understood. For tech support, I made a point to see people in person when they put in a request, and asked them to show me what they were dealing with. This proved a good way to avoid mistaken assumptions and unwanted surprises. Over the years I've learned that this is also the foundation for building empathy and connection; if you practice understanding first, you will see huge improvements in your relationships.
The lessons in these books proved both pivotal and timeless because they are founded on principles - in the "basic truths about the world" sense of the term. My favorite lesson of all from that time period might be called a principle of principles: For best results, align your intentions and actions with truths about how the world works.