Procedure for cleaning battery contacts?

[BlackTracer]

I found this topic
viewtopic.php?f=7&t=21076&hilit=contact+cleaning
but it is not very clear on the procedure for cleaning the contacts.

I have a P2V+.

Do you clean the contacts within the batt compartment or the batts themselves or both?
How do you do it? What is the exact procedure you use? (what chemical/cleaner, how do you apply/wipe it, how much product do you use, etc.)

Thanks for any tips. I just don't want to skip any preventive maintenance. Especially in this area.

 

[BWJ]

I use this http://www.bechem.co.za/berulub-fk-122 for protection and better contact