I'm going to sell my guitar and I want my guitar to be clean enough. I need your help about it. There is something like oxidation. These are the pictures of the guitar. How can I overcome?
Thank you.

The dust where you can't reach? Toothbrush. The stained metal parts? Dunno.
Jackson Dinky (JB+59) > TC Polytune Noir > TS808 clone > DOD 250 > Modded RAT > CH-1 > GE-7 > TC Flashback > Plexi Clone
Regular polish for household metals is the best you can do. Apply it to a cloth first; never spray anything directly on to your guitar. Be careful to get it only on the metal parts and do not put it anywhere where the strings are.

That said, if it's a cheaper guitar (and by that I mean anything below an American or Japanese model), chances are the hardware will be permanently marked. Cheap hardware is not plated nicely to stay shiny forever.
Yes, I know everything. No, I can't play worth a damn.
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It depends. You need to try. Refer to Mr. Flibble's remarks for instructions. How can we know if it will work if you don't try?
I don't know if you can you rust removers. Can we use industrial rust removers?