How can someone from abroad manage the expenses of attending a private university?

Hi Alejandro.

This is indeed a very difficult task for non-German students at private universities. And this Problem has since been acknowledged by universities, the Deutsches Studierendenwerk (German National Association for Student Affairs) and the DAAD (German Academic Exchange Service).

Therefore, there are support offers available for international students.

As you pointed out correctly, one way to cover expenses is securing a job in advance.
In this regard, naturally there some things to consider beforehand.
For more detail refer to the following pages by DSW and DAAD:
https://www.internationale-studierende.de/en/during-your-studies/jobbing
https://www.daad.de/en/study-and-research-in-germany/first-steps-germany/side-jobs/

Be aware, though, that even the DAAD points out:

It is virtually impossible for students to fund their entire cost of living through side jobs. [...] Instead, we recommend that you make use of the recess period and ensure that you are financially secure through scholarships or with the help of your family.

A question about scholarships has already been raised before. See: https://www.privathochschulen.net/en/questions/any-financial-support-for-non-german-students

A pretty good, but also demanding alternative is a dual study program, as the tuition fees are covered by your employer and you'll earn a little extra.
The dual study programs comprise an academic degree and a professional qualification, i.e. study and work alternate regularly.

Dual study programs already exist in a variety of areas. To give you an idea:


You can also always contact the student advisory service at the university of your choice if you need further information or help.

Kind regards