I thought Infinity's answer was the best one with the least BS so far. My advice is along the same line. Keep a handle on your material.
Fill out a three week look ahead every Friday, that include every day for the first week and then a summary for week two and three. The goal isn't to be right, it is to have a direction and a plan that you can and WILL change.
Learn how to estimate. do your own takeoff on the job and do it early. Check your fixtures and gear against the order. Count the receptacles, switches etc. and extrapolate the number of boxes you will need and order them from it. keep this so that later you can order the right number of devices. Even before you do a true detailed estimate, still learn to do the counts.
Develop your instincts. When you send a guy in to a room to "rough in boxes" Take 10 minutes to run through it in your mind. Set a time for the person. You should have already laid out the room with paint, sharpies whatever. Tell the guy, "Go in here and rough in. There are approximately 15 devices. I figure it will take 2 hours,." Or run these conduits this way. I think it will take about 8 hours." Then when the person is done follow up. Find out where you were right and wrong. It is a fine line to make the journeyman feel like you are not second guessing him, but at the same time, that you are on top of what the work you are assigning takes.
And as another person said. Put down the tool bag. I always say that I started out pushing a broom and then I graduated to a pair of Kleins and then they promoted me to a pen and a broom.