Take your tissue paper and cut it into small squares. Again, about an inch by inch will be good. You will want to have a skin color as your base. You will also want to have detail or accent colors for the mouth or eyes, etc. These pieces can be cut into the shapes that you are looking for the accents to be. In the example, we have white eyes, with blue dots, a red mouth and pink as the base. The lighter the base, the more coats of tissue paper will be required to cover the area, particularly if you used newspaper.
Once the newsprint is dry, you can begin to use the Modge Podge. Taking the sponge brush, paint a small section of the balloon with the Modge Podge. Cover that area with a small square of tissue paper in your base color. Place a bit more Modge Podge over that area. Repeat this until the entire balloon is covered with the base color of your baby head.