Visit with your predecessors from previous Administrations. They know the ropes and can help you see around some corners. Try to make original mistakes rather than needlessly repeating theirs.
Don't necessarily avoid sharp edges. Occasionally they are necessary to leadership.
Don't be a bottleneck. If a matter is not a decision for the President, or you delegate it. Force responsibility down and out. Find problem areas add structure and delegate. The pressure is to do the reverse. Resist it.
Be precise. A lack of precision is dangerous when the margin of error is small.