Best result: buy new
Second best: take to a body shop to be tanked and powercoated
Doesn't work: clean with solvent, sand, spray paint
Cheap: clean with solvent, scrap with black disk for drill -- looks like coral,
or a dirty nearly-petrified sponge, works better than any wire brush, then
clean again with lacquer thinner, then paint where rust was with rust converter,
then wait 1.5 weeks for rust converter to *really* dry, then paint with spray
paint.

B.