Determine that this is the career choice for you. Such a degree is exacting in its demands and somewhat specific in what it prepares you for. Higher education administration is a management degree of sorts, so you will learn skills that will help you in many upper-level positions.
Consider which school will best serve your needs. There are many schools available, and even some online programs that promise you a Ph.D. in education, but each school and program has its own focus. Contact the various schools that interest you and talk with those who are likely to become your professors.
Look at the differences between a Ph.D. and an Ed.D. There are those who maintain that the Ph.D. is the superior of the two degrees and that the Ed.D., which doesn't necessarily require research or a thesis, is a rather variable program from university to university.
Decide which aspect of higher education administration you want to be part of. Would you enjoy learning about community college leadership, special education, or would you prefer K-12 educational leadership? You need to be clear on the ultimate goal so that your studies can be directly relevant to what you want to accomplish.
Be aware of the two stages you have to go through before being awarded your Ph.D. In the first stage, you are a student, when you take all necessary course work. In the second stage, in which you work on your dissertation, you are considered a true candidate for the Ph.D.
Pass all oral and written tests and write a carefully thought-out thesis. The idea is to extensively test your knowledge of higher education administration and your competence to act as a professional in the field.