I have tried this both ways.
The first way is - ironing. Hot and sweaty work, and you will forever be worried about any little potential wrinkle...

The best way is to keep it "perfectly wrinkled":
Moisten slighly - with a (whatever it's called - little spray bottle thingy which makes a mist). Then crumple up. Crumlple again. And again. Putting it in a wad on the floor and jumping on it can be fun, as can be kicking it around for half an hour or so.
Leave to dry.

Check wrinkles, repeat procedure as necessary