When sanding a stock use some masking tape over the checkering and then trim it along the outside edge. Make sure that you use a small sanding block and not your fingers except in the small radiuses. That will make sure that you don' t get any wavy lines in your wood and it will also keep you from rounding over the butt of the stock. Make sure that you sand in the direction of the grain of the wood and not across the grain. You may not be able to see the scratches in the wood but when you start applying the finish I can assure you that they will show up.

Have you ever refinished a stock before? What kind of stock is it?