There are a number of different applications that use the XLR connector, that require very different types of cable. The XLR connector is commonly used for microphones, speakers and DMX lighting controllers. The cable in between the connectors has to be of the correct specification to support the voltages and resistances concerned with each different task. Failing to check the cable is of the correct specification can have varying results. Using a microphone cable in a DMX system will result in a weak signal that is prone to interference. Using a microphone cable in a speaker could result in a sudden short that could damage equipment or harm anyone attempting to connect or disconnect it.
The order in which cables are connected is important for protecting equipment from sharp voltage spikes. Where possible, all devices should be powered off before connecting an XLR lead. The voltage-balancing properties of the cable do not protect the gear from short circuits. If connecting a microphone to a live mixer, connect the cable to the microphone first, then turn down the gain and volume on the appropriate mixer channel before connecting the plug to the mixer input. Connecting the cable in the opposite order could result in a live part of the cable contacting an exposed surface in the microphone. This could burn out internal components in the mic, or shock anyone holding it.
The cable inside the plastic insulation is made from a twisted spiral of dozens of thin copper fibers. Though they are strong together, twisting and sharply bending the cable can fracture individual strands of the core, gradually weakening the signal strength that the cable can carry. When finished with XLR cable, coil it gently into a loop, two to three feet in diameter. Roll the cable between your fingers with each turn of the loop, to preserve the spiral of the fibers inside. It's difficult to describe, but you can feel the cable resisting the loop if it's done incorrectly. When you find the "sweet spot" the loops of cable will hang perfectly parallel to one another.
Having rolled up your cables neatly, it's important to store them in an appropriate container for transit. Any sort of bag or soft container is not recommended. If the cables are bundled together on top of one another, and allowed to shift around, they can easily become tangled and snare one another. Untangling a bundle of cables is one of the ways in which they can be damaged. Instead use a solid container such as a box or a bucket. Gather each cable up and secure it into its own discreet loop before putting it into a container. Keeping them separate and secure is the way to extend their lifespan.