DO NOT DO THAT.
Your original thread was introducing yourself and telling us where you came from. Now, you changed the title and content of the thread, making all replies nonsense.
I have just come in contact with DB 12C, there is no best practice of parameter adjustment.
If there was a best practice then Uncle Oracle would set it for you rather than let you get it wrong.
Repeat after me "Default is usually fine. I don't have a problem unless I can identify a problem."
Start your reading with the concepts https://docs.oracle.com/database/121/CNCPT/toc.htm
ONLY once you've read and understood the concepts should you consider looking into changing anything.
how to delete this discussion ????
As you've messed up the discussion by editing the original content (which you should not do) I shall lock this thread, and you can try again.