slow is best when you're learning new.
ftr though, i tried chalking my file(s) when draw-filing my current project's colerain bbl. it cause more problems than it solved. seemed to make shavings pile up and gouge the bbl. that's exactly what you want to avoid. carding is good, but my chalking experience with steel was a no-repeat deal. i'm sure it's the best way to file non-ferrous items, but mile mileage certainly varied from common lore wrt draw-filing steel.
file, then 80 grit, stay with 80 until all file marks are gone. if you gouge with the file, you may want to go back to the file to remove the gouge-marks... careful not to repeat them.
then 120, 150, 220, or so-until you get to the desired finish., never moving fwd until all previous grit marks are removed.