First, it really is this simple. You draw a swirl on a piece of paper and cut it out. The bigger your swirl, the bigger your flower. If you use an entire 8.5x11" piece of paper your flower will come out to be approximately 2.5-3" in diameter. Here are the sizes I have drawn:
Like I mentioned earlier, the largest swirl will create a flower that is about 2.5-3" in diameter. The middle swirls will create a flower that is about 1.5" in diameter and the smallest swirl will make a flower that is less than an inch in diameter.
The second tip is that depending on how wide your swirl is, the flower will look very differently. The petals will be as tall as the swirl is wide. So, in the picture below the swirl on the left will be a very flat flower and the swirl on the right will turn into a taller flower with more dimension. I used a combination of both of these, however the wider swirl is MUCH easier to cut.
The next step is to cut out the swirl. Once you are done it should look like this:
Then, place the swirl with the pencil markings down and begin to roll the edge towards you:
Now grab the rolled paper and leave a bit remaining at the end and use your glue gun to place a generous amount of glue where I have drawn the pink X. Keep one finger on top of the flower like shown below and press down onto the glue and hold for a few seconds.
They are a bit time consuming to make, but once you get the hang of it it's not that bad! Here are some more pictures of what I have used the flowers for: