Frequently, I use oil paints for portrait work on larger canvas. I like the tradition behind it and the fact that it allows me to develop the image slowly and deliberately. I usually save this for studio work. If I have more limited time or am traveling by car, I use acrylic paint. For portrait work, it challenges me to plan ahead, work more quickly, and use a smaller canvas. Through the years, I have chosen to use watercolor and/or ink pens when I am traveling by air or train. For me, they are lightweight, easy to pack, carry, and use in cramped or inconvenient places. I either use a small bound journal or I cut up Bristol board and cold press watercolor paper in sheets of 5 X 7 inches.