Draw the foundational figure lines. Start with a vertical balance line; it should be centered on the page and take up about four-fifths of the length of the page. Divide the line into 10 equal parts and draw hash marks to indicate each part. The top part is the head, so draw an egg shape there with the narrow end pointing downward. A third of the way down the second section is the where the shoulders are. A quarter of the way down the fourth section is the waist line. The length between the shoulder line and waist line is also the length of the shoulder to just under the elbow. The hash mark at the bottom of the fourth section is the hip line. Halfway down the fifth section marks the end of the torso (crotch line). The legs extend below so that the knees sit three-quarters of the way down the seventh section and the ankles at the top of the 10th section. If the figure is wearing high heels, the toes meet the level of the bottom hash mark. To give the figure a greater sense of action and movement you can curve the center line of the figure's torso so that it doesn't lie directly on top of the balance, but keep using the marked balance line as a guide for where the parts end and begin.
Draw in the body of the figure using the foundational lines. Centered on the torso's center line, draw a line for the shoulders that's one and a half head-lengths long. The waist line, centered on the center line, should be one head-length long. The hip line is only slightly narrower than the shoulder line. Connect each line's ends and you'll have an hour-glass shape with a long top. This is the torso. The arms and legs should be lean, in order to give the illusion of greater length. Draw in the legs and arms in the pose desired, but keep the body's center of gravity on the balance line.
Sketch in the clothing. Start with the larger shape of the outfit's silhouette and work your way down to smaller details in the clothing or accessories. As you draw, keep in mind that your rendering needs to give a striking impression of the fabric and color. Focus on the most striking aspects of your design and accentuate them. You already have a figure with legs as long as the Nile, so accentuate a flowing skirt so that it shows movement in the way it's draped.
Color your sketch. Watercolors, markers and inks are intuitive options for coloring in the rendering because they are ideal for quick completion. Keep your painting style in the same world as the mood of your design. If your rendering is meant to go to a draper, paint it in so that there are hints as to where the seams and closures may be on the garment.
Use the white space left to render any finer details. These details can be stylized like the figure rendering, but they need to be drawn on a larger scale. The idea is for the viewer to be able to know what all the pieces of the garment are, and get a sense of the mood that the rendered clothing evokes.