Quick portrait (Pencil Drawing)

I went to Mahabaleshwar with a group of friends. It was raining heavily and it was very cold in the morning. While we were chatting before the breakfast, I was sketching the people around. The senior-most member of our group (Age 75) was sitting next to me. His head was covered with a scarf, which I could not resist drawing. The time was short since he did not know that I am sketching him. So this was done real quick, less than 5/7 minutes I think. I again drew the contour first and then the details inside. This approach is helping in improving the proportions.