GoKawiilThe first thing you should do before you clean your device's USB port(s) is to power it down. When dealing with a desktop PC, make sure you unplug it from the wall. Once you're confident your device isn't getting any power, it's then safe to go to work on its ports.
In terms of what you're likely to have lying around your home, a plastic or wooden toothpick is your best bet for cleaning a USB port. This simple household item can easily remove lint that may be residing inside a port, though it's important you use toothpicks delicately when cleaning electronic devices. Don't apply excessive force when brushing the inside of a port. Instead, use gentle thrusts to weed out any dirt or grime that may have gathered.
If you want to go one step further, a can of compressed air can also be an effective tool for cleaning USB ports. In tandem with a toothpick, short blasts of compressed air can dislodge dirt and dust. Just be sure not to press the can down too long, as continuous blasts of air could potentially damage a port's connector pins.