When doing portrait for figure drawing work I usually work in a medium scale, not too big. It may depend on who the person is that I am drawing or painting, the surroundings, and whether or not I am doing their entire body or just their face. Once I have everything in place and the model is in a good position, then I am able to start, but no right away. First, I would do a gesture drawing to see what I want to do; make sure the proportions are right as well as the scale before I actually go into the final piece. My professors always encourage students to approach their work in this way rather than jumping right into the work without, and this is very useful in many ways. After I have a gesture drawing of the model done I can begin on the final piece. I want to make sure that everything looks right; if I am doing a full body pose I want to be sure that the scale of the model is proportional to that of the drawing or painting, which ever I am doing at the time. This would include the legs and arms are of equal length, the head of the model isn't too big or too small, and most importantly, I want to make sure that the angels and perspective are well balanced. If I am working on just the face of the model, I want to be sure that head covers most of the paper or canvas, which ever surface is being used. For the facial features I want to place everything at equal distance and proportional, just like it shows on the model. The eyes aren't too close or too far apart, not too wide or too narrow, the nose is about the same distance from the lips and the eyes, and the tip of the ears are about at eye level and the bottom of the ears are parallel to the bottom of the nose. These are just a few examples of what to check for. Not every person is going to be the same so you have to patient and on point. Take a step away from the work for a minute or two to see how it looks from a distance because this will let you know if you need to make any changes. Up close things may look to be ok, but if you step back and look from a distance you may find things that need to be fixed, so do this a few times just to be safe. This process works for me and it has helped me improve in my work a lot. For anyone that loves to do portraits and figure drawing I would also encourage them to take these steps as well. Your skills will improve over time.