Shell, before you use your new mat wash it. Throw it in the bath tub with a little mild liquid soap or detergent, slosh it around then rinse it well and let it air dry. It will be a lot less slippery when you first use it.
Good for you using the ball for crunches. That makes them doubly hard. I have a ball but have yet to blow it up. I flunked ball work somewhere along the line so just use the floor. The very best ab workout is remembering to hold the tummy in as much as you can. (Wonder if Ginkgo would help in that department..j/k) Kandee