In Eric Fortune’s case he used an actual picture of a person as reference. He took a picture of this person in the pose he wanted where he wanted and drew his piece from this photo reference. He transfers the sketch to watercolor paper, finding it helpful to correct anatomy on better paper. Another way Eric uses reference to is leave the drawing in a sort of rough state so as not to disturb the paper with erasing. He tries to get enough information from the referenced pencil drawing portion of the work, letting the paint do some of the detail work later on.
Amit good response. I can see you improving through the use of reference in your sketches