The very best administrators have done the jobs themselves that they will later over see. If you do it yourself, you know what is reasonable and what is just an excuse. Most teach for several years before moving up the ladder. There are few entry level jobs as an adminisrator. If part time jobs are what is called for while you are in school, anything that puts you in contact with the students and faculty from classroom aide , busdriver, or even serving in the cafeteria. You can’t expect to successfully tell others how to do a job unless you have done it. Other helpful skills are assistant in the office, try to get an understanding of keeping up with supplies.

Any job that you will later supervise, is a good one to have now. The more variety the better.

The best experience would be actually teaching. Most, if not all educational administrators have a background in teaching. I’m guessing you mean principal, asst. principal, asst. superintendant, those sorts of jobs, right? You need to have a teaching degree and some amount of experience under your belt before you can be hired for one of those positions I would imagine. Good luck– it’s a great field to get into!