I lead teams that sell software and drive customer success.
One of the things I love is that I don't have a routine day. Some days are spent face to face with customers all over the world, helping them see how our products can help them overcome their business challenges. Other days are filled with internal meetings over web conference/phone, where a great day is helping people solve problems and reach their goals.
Most of what I do at work wasn't learned in the classroom. The most important skill in my job is communication. That involves a lot of listening, not just to what a person is saying but to what they're not saying. Reading their facial expressions, tone and body language. Empathy and emotional intelligence are HUGE. Prioritization is also tremendously important. I always have too much to do, so figuring out what needs to get done now vs later vs not at all is big.
Here's the first step for high school students
Understand your core strengths - what are you inherently good at? What differentiates you from your peers? Figure out how to exploit and expand that. Then define and prioritize your gaps - what are you not good at that will be important in your path? Start closing those gaps.
"You're an engineer, you can't do sales."