On the list of things we enjoy doing, we'd put ironing somewhere at the bottom of the list, inbetween scrubbing toilets and watching repeats of Mama's Family. Still even further below on that to-do list is actually cleaning our clothes iron. We just inspected our iron's sole plate, and found there was a noticeable build-up of cooked on spray starch, which was impeding smooth movement.
We initially tried using a magic sponge on the bottom, which resulted in a slightly cleaner iron bottom than before, but with noticeable residue remaining despite our gumption to remove the build-up. So we resorted to a household concoction of baking soda and a little water, forming a thick paste, which we then applied to the iron using the magic sponge. With a bit of patience and elbow grease, we got almost 100% of the residue off the iron bottom. Just be sure to avoid clogging the holes on the bottom of the iron (oops, we didn't realize till afterward of our misstep).