Fill the balloon with water . This image illustrates why you don't completely fill the balloon you should always leave some room in the neck of the balloon, then as the form dries the pressure has somewhere to go and your clay wont split.
How to make tiny pom poms with a fork. Wrap yarn around fork until fat, then cut. Take a small piece of yarn and tie entire bunch together so that the knot fits through the prongs of the fork. Take off of fork and cut all the loops.