Most of these things I learned from my old life in restaurant management but I feel they are still useful in the airline world.
1) Relax and don't sweat the small stuff. Unless it's something that will make the airplane fall out of the sky there is no need to get huffy and puffy.
2) Don't lose the forest in the trees. Meaning don't get so wrapped up in the minor details that you lose your overall perspective of the operation. If you find yourself starting to lose the "big picture" then you are doing too much; delegate some of the details until you can catch up.
3) Trust your coworkers until they give you a reason not to. We're all professionals. Nothing kills the initiative and enthusiasm of a good FO like a micromanaging, overbearing Captain. If you want to treat me like I'm still on IOE then maybe I'll just have to act like it.
4) Take care of your people and they will take care of you. You live and die as a crew so take care of each other.
5) Attitudes are infectious, so try and be positive. Just because you hate your life doesn't mean everyone else does. If it doesn't affect the operation or add to the camaraderie, we don't need it. If you have an axe to grind with the company or just
have to discuss your financial, marital or physical problems and how the whole world is pooing on you, lets do it over a beer at the bar.
6) Don't be selfish. I hate the guys who fly slow and arrive late every leg just so they can make a couple extra bucks. If you're already late, pick up the pace. Is inconveniencing 50+ people as well as possibly your crew
really worth an extra $7 in your pocket?
Really? (I once missed my flight home because the tool bag
RESERVE captain I was flying with wanted to pad his TPIC time with a request for the arrival runway furthest from our gate followed by a loooong, sloooow taxi. Lucky for me there was one more flight home...3 hours later.

/rant.)
That's what I have on my list so far for if/when I ever upgrade. After 3.5 years in the right seat, I've seen a lot of what works well and what doesn't and take a great deal of interest in observing the habits and attitudes of "bad" captains just as much as the "good" captains.