When folding the main, it's usually easiest to do it on the deck. When lowering the sail keep it on one side of the boat. I usually then put the head in the cockpit on the other side of the boat then stack the rest on top until I get to the foot. Pull the foot off the boom then fold on the clear side of the deck making sure not to fold the windows. I don't try to use the same fold every time.
Many small wrinkles are probably better than a few big ones.
While folding check for any tears or worn areas. Areas to check are around the middle of the foot where the runners hit and the batten pockets. If you are getting any rips in the foot you probably need to tape up the runner shackles and pins.