Detailed Review Of Preparation

When you want to be PSPO-I certified, It helps a lot that you have thorough scrum knowlegde. What I can advise is:

Have a good understanding of the scrum framework
* By getting the PSM-I certificate
* By reading a lot of blogs/podcasts/books about scrum (Liberators/Gunther Verheyen/Geoff Watts and more)
* By doing an official scrum training

After that, focus on the PO specifics, like optimizing value.
* By reading a lot of blogs/podcasts/books about the PO role

And, do a lot of open practice exams on scrum.org!

For me, it was about learning about the role some more. The result was getting certified. It was also the check if I did understand what I learned. The certificate as the only goal is not the way to go ;-).