Making old nuts, bolts and clips new again

How did you do it?.....

I'm getting down to the reassembly of a lot of the sub assemblies and I have dozens of labeled yogurt cups full of screws, bolts, nuts clips etc. and since I have painted or powder-coated everything so far I don't want to use crusty and rusty fasteners on these nice clean parts....

So tell me how did you get yours cleaned? and with what you cleaned them with?, then what did you use to coat them afterwards.

I'm all ears.