Sweep off the steps to remove all loose sand and dust. Those loose particles of filth will only get in your way.
Don a cotton surgical mask to protect your mouth and lungs from the sand of the stone and the chips of the paint. This is especially important when you do not know what type of paint covers the surface of the steps, because it may be toxic in large doses.
Rake a metal file over the face of the steps starting with the top step near the very edge. Work your way across the entire top of the stone. The surface of the sandstone should come away easily because it is so soft.
Scrape the stone until you are able to clearly see the tan color of the naked sandstone below.
Reshape the steps of the stone using the file if the steps become a little less defined as you clean away the paint. Scrape the file straight across the vertical part of the step and straight across the horizontal part of the step to make the edge more defined.
Sweep off your steps regularly to check for any missed spots of paint. Wash your file off regularly as well to ensure it is working to maximum efficiency.