There are a few simple things you can do to maintain your headphones.
When connecting your headphones to an audio device, make certain the headphone plug is fully inserted into a jack or adapter. You may only get a single channel of audio if the connection is not complete
Check your headphone cable to make sure it is not cut or frayed. When disconnecting it from an audio device, do not pull on the cable—instead, grab the base of the headphone plug or audio attenuator and pull gently
When not in use, store your headphones in their carrying case. The case protects them and keeps the cable organized