I have observed a number of quite successful administrators, and here are some lessons:
1. Your job is to get the place in shape. If there is unfairness, waste, idiocy, lack of organization, ... what you want to do is to get the place in shape. People who have special privileges need to realize the party is over, those who are sloths need to realize it's time to wake up, etc. If people have stopped doing research, you want to get them back on track--incentives, positive and even punitive.
2. You do not count. No special favors for your friends, your partner's friends, your friends' friends, people who work in your field, etc. If there are fishy procedures or processes, straighten them out. It's all about making the place good enough that you can leave for the next job. IF YOU JUST WANT TO STAY IN PLACE, SAY UNTIL YOU RETIRE, YOU SHOULD RESIGN--SEE #5 BELOW.
3. There are bound to be loads of points of friction: those who benefit from the past (rent-seekers), those who have special privileges or who are getting away with not doing their jobs, etc. You are cleaning house. While you are doing so, don't leave behind garbage for your successor.
4. Don't get in battles with anyone, at least battles that look like battles. You want to have things just happen. If the higher ups won't help, AND they are stopping you, they need to realize that your job is to clean up the place. If they won't go along, start looking for another position, or just go back to being a professor. Don't be an instrument of someone else's corruption or revenge--even your most reliable colleagues will use you to do their dirty work.
5. You don't need this job. You almost surely have a tenured professorship. If you can't make a difference, get a research grant and go to work.
6. Don't antagonize your strongest faculty. They should be your allies, but if not you don't want them as your opponents. Of course, ala #1 above, you will need to ensure fairness, and that may mean problems, but blame that on the higher ups such as the provost or the president and the board.
7. Every few years, ask yourself, What's the next challenge? Keep in mind that you need to resign when you don't see a path forward.
8. It is quite unlikely that you are as strong as your strongest faculty. Just because you are dean or provost, does not mean people should respect you as a scholar.
9. There are now no clawbacks for deans or provosts who make big mistakes. But every time you appoint, promote, or tenure weak faculty, or fail to retain your strongest faculty, you are leaving a disastrous legacy (disastrous since it may have effects for 10-30 years!). I have always felt that deans who advocate and tenure faculty that 5-10 years later turn out to be mistakes, should have clawbacks attached to their salary or emoluments.
10. Everyone knows that provosts should never buy a used car from a dean, since the dean has more more information about what is going on and is "selling" only some of it. Deans are protecting their faculty and departments, but in so far as they do so they are likely to be protecting disasters waiting to happen.
11. You are in the sales business, promoting your units or university. Keep that in mind, and don't be deluded by your own patter.