Sketch a fashion figure walking with one leg forward. Slant those shoulders and hips for fashion attitude.
Draw pants. Angle the waistband with the hips. Keep the knees together, as in #2. And for the back leg, draw the hem of the pant leg curving downward for perspective, as in #3. Keep the forward leg long and directly under the head, as in #4.
Draw a shirt and finish the illustration with fold lines curving into the body to represent the clothing moving with the body as your model walks.