We use our iron a lot. Weekly. We have had our iron for a few years, and it was in desperate need of a good cleaning. I found a tutorial from Real Simple, which you can find here.
You basically make a water and baking soda paste, rub it all over the iron, wipe off with a damp cloth, clean the holes with a q-tip, fill the iron with a vinegar solution, and steam out the vinegar and water until your iron is clean.
The longest part of the whole thing was steaming out the vinegar solution and making sure all residue was removed from the iron. I tested the iron out on a few old shirts before using it on Steve’s nice shirts just to make sure. Let me know if you have had any luck trying any other methods!