How to coil cables
This is how you should coil cables in the film industry. This is to stop kinks and knots that end up destroying the inside of your cable. You want to keep your cables in the best condition possible, without them you are stuffed.
This video easily explains how to coil cables and with a little practice you will be doing it in no time. When you have the cable wrapped up fully you should be able to hold onto the end and throw the rest out and it will go in a straight line. Very useful out in the field when you need to get a cable to your boom operator.
Other Cable Management Tips
Make sure you look after your cables by cleaning them and protecting the connections from water. You can do this by using gaffer tape or wrapping in plastic. This will ensure that you won't get any interference or even distortion from dodgy connections.
When you have multiple cables running into or out of your mixer you may want to tag them to track what is going where. The easiest way if to try to colour co-ordinate them so you have a black cable for your boom and a different colour for radio mics. You can then tag the separate radio mics with 1, 2, 3, 4... to represent where they should be plugged into the inputs of the mixer. The easier to are to find and connect things the better, especially for those last minute changes on set.
After you are packing up and you remember how to coil cables, be sure to store them properly to save on tension within the cable from being stuffed in a box. Kinks and bends will end up degrading the cable in the long run and make coiling cables harder.