Officers, what is the best advice you gave an NCO?

When the time is available give your subordinates your rationale for why you made the decision that you made. It will help you in multiple ways. First, if someone understands when there is time, they will be more inclined to act with decisive initiative when you need them to and can't give the explanation. Second, it allows you to grow leaders because you show them how you made the decision and in the leader development job that we are in this should be a top priority.

You're in a unique position to train your future leadership. Remember that your new Lieutenant may be your son or daughter's Battalion Commander some day. Use this time to develop a leader you would want both you and your child to follow.

Set long term (>5yr) and short term goals to include professional development for your next career advancement maybe even a more attractive MOS for advancement. Those goals should include education, there are so many opportunities in the current force to get a higher education, (TA, program, formal schools cross credit, ect...) Keep working on it a little at a time and before you know it you will have a degree. Keep focused on your goals and do not let daily setbacks impact the big picture.

Not being an officer I still thought I'd share the best advice given to me by one:
"Don't be afraid to tell a superior that you can't do something, we are going to ask a lot of you and if we overwhelm you with too much, let us know. We can either push suspense dates out or reassign the work. Don't let us burn you out."

I'm not a commissioned officer, but some of the best advise I ever got was "map your career" from my Scout Sniper Platoon Commander (Assistant S2). He spent a couple hours with me one afternoon, and walked me through billets & schools I'd probably want to hit in order to be competitive for promotion both in the short run & long run.

Small unit, big unit, B-billet, school house, etc. Which boxes I would need to have checks in.