How to take care of the Usb Ports?

I have a 2013 macbook air with two usb ports. When using it as a desktop, I usually use the left one for my backup drive, and the right one for my usb hub with my mouse, microphone, etc. When using it as a laptop, I still need one for my mouse.

I also have a used Kindle Dx. I have proprioceptive issues and can't use touch devices. It can't connect via the usb hub. It can connect through the left usb port, but quickly drops out. It can connect through the right usb port, and sometimes drops out, but sometimes stays long enough to transfer files.

I suspect most of the trouble is with the Kindle, but it's clear that some is with the left usb port on the Macbook. What can I do to avoid deterioration of the right usb port?