Cheap, easy and useful thing I've done with the cords on all on my mobile devices, including 30-pin connectors:
As soon as I get a new cord, I put a small bead of red nail polish on the side that should face downward (on the plug of both ends of the cord). Dry before using. (I mention that for those types who managed to ruin their Kfires, for instance, lol.) That way, I can immediately see the red when plugging, and know which side to plug downward. In the dark, I can also feel the small bead of nail polish, like with Braille. So no matter what the conditions when I plug a device, it's easy. Been doing it for years.