Crumple your parchment paper
Crush it to make it behave
So you know how parchment paper (aka baking paper) comes off the roll all curled-up, and refuses to sit properly on your baking tray? Just screw it into a ball. Properly crumple that bad boy up, then uncrumple it and it will lay flat, without affecting it's parchment-ness :)
Some people suggest wetting the paper, but I never need to do that. Keep it quick and simple :)