Start with a rectangular piece of fabric wide enough to go around a little girl (about 24 inches) with a 1" seam allowance.
With right sides together, sew the ends of the rectangle together and press open.
Press down a 1" waistband all the way around the top of the skirt. Don't worry about folding it under twice - these little girls won't care if it's professional looking!
To sew the waistband down, start on the right side of where the seams meet up, securing the stiches by backstitching a few times there. Stitch all the way around until you come to within 1 1/2 or 2 inches from where you started. Backstitch and make your ending secure. Now you have an opening wide enough for your elastic to go through and you'll stitch the hole together later.
To get your triangle cuts to be uniform, cut a piece of paper and draw your angles with a pencil. Make sure to cut off the pencil markings.
Add your elastic to the waistband, stitch the opening closed, and you're done!
(I'll post instructions on basic elastic waistbands soon...)