I had one of these:
Remember? I didn’t want a shiny tush.
So now I have one of these:
Unpick the elastic waist. Remove the side hanger loops. Open out the waistband casing.
Unpick the skirt’s side seams far enough to comfortably fit your arms, the same distance on both sides.
Turn the skirt inside out. Press down the seam allowances to sew — don’t open them out. I used a long stitch set to wide zig zag.
With the skirt still inside out, pin a few inches at the top of what used to be the waist. These are about to become your shoulder seams. Keep fitting and pinning until you like the way it looks and fits.
Stitch both sides.
Press down the seam allowance at the neck, what used to be the waist, between the shoulder seams. Stitch both sides or finish as you like.
I used a knit skirt with a little stretch so the top fits over my head. You could also put in a keyhole closure in the back if you need to get the thing over your noggin. I might try that on the next one.
In the end, since the skirt had some curves in the sides to accommodate hips, I ended up straightening the side seams a bit so the thing wouldn’t poof out.