If you have space, leave your mat unfolded on the floor so that it stays flat. Otherwise, roll it up, printed side up, so that it can go back to its original form more easily.
There's an ugly stain on your mat?! Keep calm and grab a soft sponge soaked with soapy water to gently remove the stain. Be careful not to use the rough side of the sponge.
Things to watch out for: direct sunlight, claws, and jewelry.