I've made a couple then I put my own tweaks on it to make it easier for me.
What you will need:
needle and thread (to match, optional)
freezer paper to cut out the felt.
Cut out about 5 circles of the same size.
I cut out two different sizes just to play around.
I found the larger the petals, the easier it was to hold. But after a few of the smaller ones, those became easier too.
Make sure that you have the end of the thread in a very thick knot so the thread doesn't pull all the way though. I tied mine about fours times around.
Then stack all five folded circles nice and neat together.
As you do so, it may give you a little trouble to stay looking like a flower. (the first couple of flowers really tried my patience) I found that just playing with the placement of the petals before and while you are sewing will help get the best results.
I also found that gripping the flower like pictured helped with the petal placement. Then I wove the needle and thread through all the petals again and pulled thread taunt for the flower to hold its shape.
Next, tie a knot or two to finish off the flower. And you're done!
The first one is very flat. The second starting to show the curve of the petals.
Practice makes perfect!