The practical way to become Oracle Certified Master (OCM).
1) Be Oracle OCP first. If you don’t know what that is, stop here.
2) Take 2 advance trainings from Oracle University. recommended trainings (RAC and SQL tuning). Taking the training, you can play with RAC at your will without any concerns. RAC in the Oracle lab doesn’t belong to any production instance, so no worries at all. Furthermore, refreshing your knowledge of tuning is always good. Your experience from work only can’t substitute as the full toolkit of Oracle — which is what you are tested on.
3) Register for the OCM test (in many cases, the test will be in another city)
4) Book plane and hotel then take 2 days to become OCM
Get a hotel close to Oracle building though it is probably expensive. Don’t get lost in train/substation during rush hour — get a hotel close enough to walk to the exam.
5) Get results in one month.
On successfully clearing the exam you will get ‘congratulations letter’ from Oracle in a month, then a T-shirt some weeks later with the OCM logo.