Date: September 19, 2019
PMI-ACP stands for PMI Agile Certified Practitioner. It is an agile project management certification from Project Management Institute (PMI) in the United States. PMI-ACP is one of the several certifications in the agile field.
The basic requirements and process can be found in the PMI-ACP handbook on the PMI website.

Why did I pursue the PMI-ACP?

Given I already have the PMP, and agile is quite a hot topic at the time, pursuing PMI-ACP enabled me to learn agile and gain professional development unit (PDU) for PMP.

How did I prepare for the PMI-ACP?

I started in March 2019 when I attended a PMI-ACP bootcamp. After that, I submitted the application and the one year time limit began. I was lucky that I was not selected for audit.
Before the bootcamp, I knew there are many different agile methodologies, such as Scrum and Kanban. But just the high level stuff.
Throughout my preparation, besides the course notes, I used 3 resources mainly:
I used the RMC2e as the main text because it neatly organized the topics according to the exam content. As for HFAgile, it tended to group the main agile methodologies together.
The material from PMP was quite useful to review because some of the agile topics are related, such as resource management and stakeholder engagement. The key idea was to change your own mindset to "think" and "do" agile. In another words, say to yourself "change is good". That's a start.
Understanding and appreciating the Agile Manifesto will help transforming your mindset.
I noticed the Agile Alliance website has some great info, especially the subway map summarizing the key practices of various agile methodologies.
During my preparation, I did the following:
The strategies I used during the exam were:
During the exam, for me anyway, I felt there was not enough time to complete all questions when I reached like the half way point (question wise). So I kind of speed it up in the second half. When I was done with the questions, I got like 30 minutes left to review. During the review, I skimmed through the questions and my selected answers, not changing answers.
All in all, I found the PMI-ACP was somewhat easier than PMP. Maybe I was already familiar with PMI exam format (PMI-ism) or simply I already have an agile mindset.
The notes I made during my preparation can be found here.