Do you wax your skis regularly? Keeping your bases nice and hydrated is probably the best thing you can do to keep your skis in good shape. A dry base is more brittle and will scratch easier. (Unless you have an extruded base, then it doesn't matter as much b/c the base won't really take wax anyway.)
Also, if you ride a lot of rails, its a good idea to detune the edges underfoot before you use them. A rounder edge will be more resistant to cracking than a factory sharp edge, b/c the impact is distributed across more edge surface.
This may seem obvious, but don't clack your skis together on the lift. If you have a straight sidewall ski, this can actually really chip them up. (I'm not saying you are doing this, I doubt its a real problem, but I have seen people do this to their skis and then complain that the topsheets are mangled.)
Try coming to the midwest, were rails are made of rust and tetinus, run ins are about as wide as my wrist, and the landings look like the first 15 minutes of Saving Private Ryan