Draw the Waistband, Belt Loops, and Flys to Fashion Pants

To indicate an elastic waistband, draw two curved, horizontal, squiggly lines. Connect the ends of the squiggly lines with short, vertical lines. Add lines going up and coming down from both curved lines to indicate gathering. Vary the lengths of the gathering lines.

Finish the pants with a center front line, the crotch z line, and some side seams. Sometimes elastic-waist pants have drawstrings, so draw those, too, if you like.