Aggressive cleaning, especially of fingerprints, can lead to scratches.
Remove fingerprints without streaking by rubbing in the direction of the grain with a soft cloth dipped in undiluted white vinegar; buff with a dry cloth. A specialty cleaner, such as Fuller Brush Company's spray gel ($7 for 22 ounces; fuller.com
), zaps smudges and helps keep new ones from showing.
Avoid chlorides, like bleach, as they can cause corrosion. Also steer clear of harsh abrasives, which are a recipe for scratches.