[oem4me]

Another fan of 0000 steel wool here on the initial cleanup. Not so much a fan of CLR though. Not that CLR does not work, it's just weak. I personally use Metal Prep phosphoric acid solution by Blue Lightning and it goes to town on the surface rust without thinning out what's left of the original paint film. Polishing later with 3M products. I find that virtually any polish/compound found on the shelf at your local chain stores isn't nearly as effective as what is available to the professional through paint suppliers, or online.
IMPORTANT: The aforementioned Metal Prep is aggressive and needs to be tested first in an area not seen. NOT RECOMMENDED for metallic finishes! It kinda bites into those metallics and can streak permanently. Don't ask how I know. Doh!

I'll include pics showing a comparison between CLR and Metal Prep on UNTOUCHED original (non-metallic) paint. That is, nothing done but spray it on and wait. No rubbing except with a soft sponge to wet it out evenly.
The acid works especially well to bring back the brightness of white areas that have turned lightly orange with surface rust.

The pic of the front panel in the bed with the two bottles shows what each product does to the oxidation after about 1/2 hour of just sitting while kept wet with a sponge. Obviously, the CLR does not do much.