my guitar has grown grime across the metal circles on its pickups

my question is: what should i use to clean the metal? wats the best way to remove the grime? and finally what can i do to prevent build up of grime on pickups?
Just wipe it off with a cloth
"Blues is easy to play, but hard to feel."- Jimi Hendrix
i use 0000 steel wool, but make sure that not even the tiniest piece of steel wool flake goes into the electronics of the guitar, if the pole pieces are rusty, which is what i think you're tlaking about, that steel wool will help you a bit.
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The questions people ask here makes me wonder how the TS's dress themselves in the morning and can shower without drowning...