You can make a girl's skirt from a pair of men's pants. Take the pants and cut from the bottom of the leg along the inside seam. Cut up the length that you will need for the skirt plus 2 inches for the waist. Repeat on the other leg. Open the pieces out. The topstitched seam that will be in the middle of the cut out piece will go along the front center and back center of the skirt. The bottom of the pantleg will be the bottom of the skirt (it is already hemmed for you.)
Sew the sides together either with a regular seam. Zig zag the seam edges if you do not have a surger so that the ends will not fray. If you would like to create a topstitched seam, lay the seam to one side- towards the back of the skirt, and sew a seam looking at the top of the fabric, about 1/4 inch from the seam.
Make and elastic waist band using 1 inch wide elastic. Make the casing by folding the top down 1/4 inch and sewing. Then fold an inch plus just a little for wiggle room and sew again, leaving a 1/2 inch opening on either side of the center back. Run the elastic through the casing and pull to adjust the size you need then sew the elastic ends together well. Hand sew the remaining closing.
You can add cargo type pockets onto the front by cutting fabric out of the remaining pants. Make a 1/4 inch seam around the sides then sew into place.