Honestly the most important thing to me is learning to stay unemotional about things when its gets crazy. Ultimately you are trying to make something. And if you get it into your head that it represents YOU, or your LEGACY or any number of things, it will mess you up. Those things are true... and they will go through your head all the time. But you have to learn to block it out on set when you have to make decisions. Cause that is all you do. Make hundreds of decisions.
And that means, learning that someone is always losing. That sounds sad, but its the truth. Someone once said directing is simply deciding who loses. Whether its the DP who won't get as nice light cause you want the scene lit for 360, or the actors who rather act a scene uninterrupted, but instead are doing a scene line by line cause you have very precise coverage you want. Or Art Department cause you are moving money to get a bigger explosion. Or SFX cause you are cutting an explosion in order to have a nicer set.
Everyone on your set wants to do a great job. They are talented and passionate people. And you have to learn how to communicate what you want because it makes those loses easier. If you just tell your DP "look, I don't care if the light won't look as good as it could, just make it happen!" Well, that sort of sucks. And they may not give you great work.
If you come up and say... "Hey, look. I know this won't be as controlled lighting as you want. But for this scene, between this two actors, I really want them to build into it, and I want them to be lose. I think its important for the performances. I want the tension to escalate naturally and I want some rawness in their staging. So, yes, we have to light for 360 degrees, but I know you'll make it look great, and it will really help the actors."
Ronald D Moore said that sometimes he just had to yell out - "Isn't this great, we are making a damn TV show." Its all perspective. If you are directing something, you are lucky to do it. Chill out. Make decisions one at a time, and make sure everyone knows what they are doing.