Etching: It's nice to have a little makers mark, or write something down into your blade. Another instructables member has a nice instructable on engraving, but I'll quickly cover it here too. You want to use nail polish, coat the blade with it, and use something to scrape the nail polish off. Write what you want with that tool. Then, you let the nail polish fully dry, and attach the positive end of a 9v battery to the metal, and the negative end to a q tip. Dip the q tip, with the negative wire, into salt water, and rest the q tip on the etching area. You should see bubbles, it's etching. Let it eat for awhile, switch new q tips, and redip in salt water. Stop when you think it's deep enough. The longer it stays, the more likely it will be less clear. Use nail polish remover to clean up.
For my mark, I used duct tape. I cut out the image in duct tape, and duct taped the blade. The metal you expose is the metal that will be etched. Then, same as above, positive end to metal, negative to q tip, and etched the design in.
Filework: You can use small files to create an intricate design into the back of your knife. I attempted a vine pattern on the back of mine. I used a round file and triangular, and filed in the vine. Then, I smoothed out the corners, to make the vine more curvy. A quick search on the internet for knife file work tutorials will yield a lot more patterns.