Manage Up! I manage my manager so he can better focus on his goals.
Juggling multiple tasks at once, prioritizing which tasks need to be accomplished first. Solving issues as they arise in a professional and courteous manner. Positively supporting other employees in their daily tasks and struggles. A roller coaster ride of time management, organizational challenges and drama. Professionally communicate positive and negative responses via email and verbally to a multitude of requests for my manager's time (a gatekeeper of sorts).
Communication skills, Solving problems by thinking outside the box and being creative, Being proactive rather than reactive to situations, Communication skills, Being professional and respectful to everyone (especially to those not deserving of such treatment), Time management, Communication skills, Organizational skills, Listening skills (listening to learn rather than to respond), Ability to "go with the flow".
Here's the first step for high school students
Anticipate deadlines and meet them on a regular basis. Time management. Prioritizing what is due when and meeting or beating those deadlines. English skills - both written and verbal (if you cannot communicate you will fail at any career). The genuine enjoyment of helping others is essential to being a successful assistant (and human being).
"The biggest in my career was: 'Maybe she shouldn't return from Maternity Leave to this position.'"