Does your best friend like to chew on electric cords or shoes? Here is a simple solution (you will need a sliced piece of citrus fruit).
When your best friend gets close to the electrical cord or near your favorite pair of shoes, stop them, tell them “no” and rub the citrus with your finger and then rub your finger on their teeth. Dogs don’t like citrus and they will correlate the citrus taste to whatever you don’t want them chewing on. You might even want to rub some of the citrus around the area. Example: rub the shoe heel and then take the citrus and rub it on the floor in front of the closet.
After you have done that, make sure to have a toy close by that you can give them and then when they start playing with the toy instead, give them praise!
Not only will you stop your best friend from chewing your things, your house will smell good!