Since I was making them for a Raggedy Ann bash this time, I decided to make this one look like her stockings: red and white stripes.
I have found that 7 layers of tissue paper is the ideal for me. More than that and the layers are too thick to separate at the end step and I get more tearing, and with less, there isn't enough poofiness to them.
After you have layered the papers and lined up the corners as best you can, fold up the bottom edge about 1.5".
Flip over the whole thing, and fold the other way, accordion style. (Like you are making a paper fan)
Round off the edges to give it more of a 'flower petal' look. Or, you could make a sharp triangle on the ends as an alternative.
Gently, gently, (remember, this is tissue paper) separate each layer from each other to fill it out into a puffy sphere.