Lay each sheet of tissue paper neatly one on top of the other. They don't have to be the same size, the first layer is smaller than the last one.
Fold the combined sheets of tissue paper accordion style.
Use wire or staples to hold the center of the flowers.
Open the tissue paper accordion.
Unfold the flower, start with the center and finish with the last layer.
When you finish all the steps, you will have something like this. Remember you can use more layers of tissue paper because it will look better.