Practice and planning makes perfect! Use a scrap piece of metal to practice your hammering techniques before moving on to the finished piece. Plan out your design or messages with a sharpie marker right on the metal.
Finishing applies to stamping as well! Patina with liver of sulfur and polish with ultra polish pads. File edges with a file, sandpaper or to speed things up, use a flexshaft and polishing wheels. Shape already stamped metal with nylon tools, pliers and mallets so as not to disturb the patterns and textures.