I've got to admit I'm a bit of a neat freak when it comes to cable management. I've gone so far as making my own analog video and audio cables so they can be the necessary length. However, I think it is most important to make sure signal cables are separated from power cords. If they do cross make sure they are at right angles to each other. I also don't like loops in any cables if possible so using cables that are as close to the correct length is important. Finally, use good quality cables (including their connectors) and most, if not all, interference issues caused by a mess of cables that look like spaghetti can be avoided.