Fabric and form: Drawing fabric using line and tone

I found the exercise very difficult and very daunting as I have never done anything like it before, even from photos. To practise I made several attempts using different pieces of cloth and different mediums in my sketchbook as follows -

a) I arranged a white cloth and did a 5-minute sketch in Pen and Ink, which was not very successful because It doesn't look very realistic.

b) A 5-minute sketch of the same cloth in willow charcoal, which was much easier as the medium allowed me to work faster and create the darks in the folds more effectively.

c) A 5-minute sketch using HB Pencil, which was not very successful as it was difficult to get the tone

d) A 10-minute Pastel Pencil sketch

e) A 15-minute sketch in Oil Pastel, which was very difficult as I couldn’t get the volume in the fold of the fabric with the Oil Pastel

f) A 15-minute sketch in Pen and Ink, which was more successful after all the practice of observing the fabric, and this time it was much easier to get the volume on the folding.

Overall I think I have improved my fabric drawing but I need a lot more practice.