painting calipers

Ok, so finally found some paint that is close-ish to the original green caliper paint on my fabia.

Now i know the results depend on the preporation, so i will be taking the calipers off to paint them and would like to remove all of the old paint as i can.

Are there any particular products that i would need to give them a proper clean and strip all the old paint off?

And would i need to put any kind of base coat or the like on before? (I am using humbrol super enamel paint for the green)

Sorry for the newbie questions but never bothered painting calipers before, but really want themn back to how they were!!

Many thanks in advance