Follow the above advice on the steel wool, and then start with 600 or 800 grit wet/dry silicon carbide paper. I personally sand wet, it seems to work faster because the water prevents the paper from loading as fast. Be very careful around the edge of the blade while sanding, even a dull razor can and will give you a wicked cut if you are not careful! (I know this from experience...)
Remember to be patient and get all of the scratches out from the lower grits before moving up, it will take you an hour plus to finish one blade. I would start with the one that says hollow grind on the blade. Be aware that you might be doing this work for nothing- if there is pitting that is deep the razor might be shot because of the thin metal of a hollow grind.

Have fun, projects are great for rainy days like today here in Texas. I will be starting back on mine shortly