I also so sew my layers together
I take off everything except the stem. The stem holds the layers nicely together until I can sorta stabilize it with my first stitch. After the first pull-through, I take off the stem, then make 5-6 stitches, like a star. Knot it off in the back.
Then back it with felt, and attach to clip/headband.
I hate glue, and I figured that it would take me just as long to glue as it would to sew, and sewing is way less messier
I've also learned that going forward, I only want to buy flowers with no glue. I can never get it clean enough when I have to "unglue".