Today (19th Dec 2018) I will start my Oracle OCM 12C study project. I will list here the topics and some study guides for each of them, so I can exchange with you who is also applying, interested or have any skills. Please comment in the post related to each topic if you find out any more valuable information to add.

My target is to take the exam by Dec/2019.

Exam dates:
https://education.oracle.com/oracle-database-12c-certified-master-exam/pexam_12cOCM