Though it might be too late for the car in question, let me offer the 
     following advice:
     
     1. If you have an original key in (near) original condition, set it 
     aside as the master for subsequent reproduction.  If you don't have a 
     near perfect key, get one "code cut" by a good locksmith or (possibly) 
     from the dealer.
     
     2. Make sure that your "daily use" keys are a relatively soft metal to 
     minimize wear on your locks.
     
     3. Check your "daily use" keys periodically to see if they're wearing 
     a lot - replace if they are, or if they become difficult to use.
     
     4. Avoid having too many keys (I'd say five max) on your key ring.  
     The scratches on the outside of the steering column isn't the only 
     damage being done!  (The weight of the keys pulls the car key off 
     center and wears the lock).
     
     -Blaine