What is the best advice you can give a Jr Officer?

I would rather you do 100 things a day and mess up 10 than do 10 things a day perfectly. Perfection is the enemy of good.

Slow the hell down watching and listening because you don't know it all

Listen to your NCO's

Treat your underlings like you would want to be treated, listen to the NCO's under your command.

1. Do not worry about looking lost or dumb before others. As a lieutenant, you can afford that. Ask the questions. Worry about actually being lost or poor judgement. It could harm others, and be a career killer. Learn, Seek advice, take action.
2. Focus on learning and gaining experience for the next higher rank, not for your current one. Take on different positions, but do not take the path of least resistance!
3. Take time to help others outside your area of responsibility. It is a small Army!
4. Develop your team. Push them up. Get rid of the dead weight within the team.
5. Keep track of your accomplishments. If there is nothing to track, you either are not doing enough or need to move on somewhere else.
5. Find mentors. The more, the merrier. Find also a personal counselor outside your unit.
6. Read on a variety of subjects. Audiobooks are great, too!

There is no single best advice, other than the Great Commandment. I hope this is of help. God bless!

Learn what you can, Study what you need.

Speaking as a Squad Leader. I have to say learn from your NCO's. they have a good grasp on what's going on and are willing to make changes to accommodate your way of doing things, but are stubborn enough to tell you when an idea is just idiotic.

Reading through the responses to your question, it seems that most of the advice would serve officers at most ranks quite well. My suggestions below are focused towards officers in general, not just new lieutenants.

Three Major Points

1. Integrity. Never compromise it. Hold others to the same standard.

2. Be tactically/operationally/strategically and technically proficient. No one respects incompetence.

3. Figure out what your boss and your boss’s boss think/value/say are the most important priorities, and focus on these. These should be clear in your boss’ and your boss’ boss’ OER Support Form and in the unit mission statement.

Other Points

1. When in charge, be in charge. You are responsible. Your chain of command believes you are in charge and responsible, and you are. Remember that, as a platoon leader or company executive officer or company commander, after your first day on the job, you’ll generally have more experience doing your job than anyone else in your platoon/company. Do your job. Note you’ll rarely have more experience doing one of your subordinates’ jobs than they have, so learn from them, and trust (and verify) that they know how to do their jobs. Remember that the training you have is valuable. Look to others to learn more. For officer mentors, look at your fellow platoon leaders, company executive officer, company commander--this group has a wealth of experience doing your job.

2. Don’t lose the Army’s equipment and make sure the Army’s equipment works. Officers are responsible for property accountability and maintenance. Junior officers will spend an inordinate amount of time inventorying equipment, because lieutenants and captains are assigned responsibility for almost all of the Army’s equipment. Failure to maintain proper accountability of property (especially sensitive items) is a really quick way to get fired and lose a lot of money (those horror stories of multi-million dollar reports-of-survey or whatever they are called these days aren’t just stories; don’t go to jail or lose your life savings because you were too lazy to take property accountability seriously). Learn the right way to conduct equipment inventories and manage hand receipts, sub-hand-receipts, and shortage annexes (yes, there is a right way). If maintaining property accountability isn’t one of your key tasks as a company grade officer, you’re probably doing something wrong, or stuck on staff. If as a company grade officer you aren’t focused on maintenance, I’d guess there’s a pretty good likelihood that your equipment doesn’t work like it is supposed to (or you’re stuck on staff).

3. Be a team player. Acknowledge and celebrate the effort of others. You will rarely do anything of significance alone. Take responsibility when things go wrong; you are, after all, responsible, and if something goes wrong, it is actually probably your fault. I’ve observed that most people respect someone who is confident enough to admit that they’ve made a mistake and be willing to learn from making a mistake. Volunteer for the jobs no one else wants. Don’t be afraid to do some actual “muddy boots” work with your Soldiers once in a while.

4. Score a 300 on your APFT. It is hard for an out of shape officer to be tactically and technically proficient, and you start at a “respect deficit” if you are out of shape. And the APFT is not that hard.

5. Never fail height/weight standards. It is hard for an officer who fails height/weight standards to be tactically and technically proficient. You start at a “respect deficit” if you bust tape. Best advice: always be below your screening weight.

6. Counsel your subordinates, including everyone you rate and senior rate. Do this formally using the forms the Army has given us. Do this monthly if possible, and at a minimum at the interval required by regulation. Put counseling on the training calendar, and protect it like you’d protect any other important event. Use counseling to set goals, review the performance of your subordinates, and solicit feedback on your own performance. Write the evaluations you are responsible for writing yourself, and solicit the input of those you rate and senior rate before and as you do so. Make subordinates do the same. Encourage your superiors to prioritize counseling (and don’t get too bitter when you realize that a lot of senior leaders think counseling is just something their subordinates are supposed to do).

7. Keep your personal life in order. Understand work-life balance. Live within your means. Remember your personal choices are likely to have an impact on your ability to do your job. Many of the things that can derail an officer in this regard are well out of individual’s control. However, many more of the things of this nature are well within an individual’s control. This probably applies more to more senior officers who have had more opportunity to screw up their personal life, but it applies to junior officers as well.

8. Be a high contribution, low maintenance officer. I’ve seen a two-by-two matrix of how officers can be characterized: high contribution, high maintenance; high contribution, low maintenance; low contribution, high maintenance; low contribution, low maintenance. Figuring out what constitutes a high or low contribution and high or low maintenance in a unit can be difficult, but can generally be understood by figuring out what your boss and your boss’ boss think are important. It is quite easy to figure out where you want to be on this matrix: high contribution, low maintenance. Leaders will tolerate a high contribution, high maintenance officer because these types perform. The Army tolerates the low contribution, low maintenance types to a point, which these days is coming earlier and earlier as the Army has stopped promoting absolutely everyone from O-1 to O-2 to O-3 to O-4 to O-5 as it has over the last ten years or so. Low contribution, high maintenance types just don’t make it anymore.

Make a decision and stick to if it needs to be corrected do it but the decision needs to be made.

Shut up, listen to your senior enlisted, and learn. It could just save your life and the lives of those who serve under you.