How to draw folds depends on several factors. The first thing to consider when drawing fabric is its thickness, hardness, weight, and texture. Cloth illustrations can have pipe folds, zigzag folds, drop folds, spiral folds, or banner folds. The number of folds also depends on the fabric's weight and material.
In general, thicker materials have wider folds that are less noticeable in the bend area at the seams. Stiffer materials tend to be pulled more. Soft and thin materials produce folds around the bands. The second concept is to recognize tension points in the fabric. These will help guide you and give you shape to your drawing.
Since tension points are basically any force applied to the fabric, if you pull, stretch, or bunch up the material, it will create tension points. Also, if an outside force is applied to the fabric, like water or wind, dynamics of the fold will change. Keep on practicing drawing until next time.
