It really depends on how good of a touch-up you want.
I've done several variations:
Touch-up, done.
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Mask, Touch-up, light sand/smooth, clear.
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Mask, Touch-up with airbrush, light sand/smooth, clear.
Now, in full disclosure, I am not a body guy.

But I have had pretty good success with the methods above.
Some of these guys on here tho, are body work magicians so, they may have better advice.
Also... Youtube university!