The first thing is to select a toned paper to work with. My favorites are Rivas BFK in taupe (camel colored), Strathmore toned paper or canson toned paper. If you use the canson it is helpful to note that there is a smooth and a rough side. The smooth is much easier to draw on than the rough. If you have not worked On toneD paper before it is easier to start with a light color. After you have some experience I would try some of the darker papers, I especially like the blues, grays and greens. Some other materials that I like to work with are Stabilio carbothello pastel pencils 645, 670, and gray, white chalk and charcoal.
The easiest way to start is to simply use charcoal on the toned paper without the addition of white. Remember that the paper will function as a value. All paper has an associated value to it, you are already using white paper for the highlight values, now with colored paper they will usually substitute for a mid-tone or shadow value depending on how dark the paper is. If the paper is a middle value, look to leave the paper showing right before the value becomes shadow, it should sit between the lights and darks as the overall value of the skin tone.
In this example the paper was a pinkish graey and the value of the paper allowed it to function in the middle value. I used carbothello pencils (645) and only rendered the values that were in shadow. I didnt have time to add white for the highlights and Im glad I didnt. The drawing works well without them and really has only 3 values. This is the quickest way to use toned paper.
This is a similar drawing using charcoal and only three values. The paper, here a medium gray, functions as the midtone values for the drawing. I again only added values that were darker than the paper, the paper did most of the work for me! This is the benefit of using toned paper, I dont have to work any harder than I have to!
This example is interesting, because the model was African American and had darker skin, I could have used a darker paper that would have taken the place of most of my shadow values and therefore I would have had to render only the light values. But bummer for me, I didnt plan ahead and so had only lighter paper with me. This means that the paper had to function as part of the lights, not even mid tone. I added white only to create the light reflecting off the dark skin and of course I had to render ALL of the shadows. This was done in carbothello 645 and white chalk.
This is another interesting example using the rough side of the canson paper. Remember I said there was two sides, a rough and a smooth right? In this example the paper behaves properly as a midtone and the shadows are added with charcoal and the white lights added with white chalk. This is the time I blow you away and mention that you can in fact achieve 2-3 values with your white chalk, based on how softly you apply it. You should be able to see at least two values here.
This was a hard one, the model had very bright light on him which plunged the top of the body into a very light value and created dramatic shadows. As a result there was very little midtone and so I wasnt able to leave much of the paper as a midtone value. In instances like this you will want to be careful not to mix your white chalk over your charcoal, be very careful not to blend or smear the two together or you get an ugly blue gray color. Keep them separate. I usually do all the dark charcoal values and then use a paper under my hand and add the white values at the very end.
This is an example on Rivas BFK, the taupe version with Carbothello 670 pastel pencil and white chalk. The paper again functions as a halftone even though it is darker in value than the previous examples. Since the paper is cooler colored I opted for a warmer tone of pastel. Rivas is a wonderful paper with a velvety feel; it is a pleasure to draw on and worth the extra cost. For life drawing I normally take a 24x36 sheet and cut into half which gives me two figure studies per page, that way Im not drawing so large that it will be hard to get the drawing done in a two hour session.
This is one of my favorite colors to work with. It is the medium blue version of canson paper. Both charcoal and white chalk show up wonderfully. Since the paper is darker it now functions as a value in the shadow tones and therefore it requires you to do more work modeling the midtones and light values with the white chalk. You will again see 2-3 values rendered using white chalk and several values in the shadows, one value being the paper itself.
Another example of charcoal and white chalk, this time on green canson paper. The trick here was that I didnt want to make the face the focal point so I forced it into shadow and by using white chalk on the back of the head and shoulders I was able to make it the focal point. The rest of the figure the white is used as a different value of light.
This paper is the darkest blue that canson makes and is very challenging to work with. The blue value of the paper now functions as the middle value of the shadows and as the reflect light that bounces into the shadows. You could really build up the light values with the white chalk here but I wanted a more dramatic darker look.
In this example I have replaced the value of the paper as a midtone and am now using gray pastel to replace it, so very little of the paper shows through. I have switched to using black, gray and white carbothello pastel pencils. Since the white is not chalk but pastel, I can now use white over the gray tone without producing the ugly color that occurs when charcoal and white chalk mix. This requires more time to build value because the paper no longer does the work for me and all the values have to be rendered completely.
This is a similar technique using black, burgundy and white pastel. The trick here is when the white and burgundy mix they produce an awful pink so I would suggest keeping them apart. You will see more paper here show through as I try and keep the white away from the burgundy.
Have fun trying different combinations of paper and pencils until you find some that work for you. I prefer pastel pencils over conte because conte stains the paper and becomes hard to erase. The pastel is easy to erase but if you sneeze or brush your hand over it, the pastel rubs off so be carefully not to drag your hand over parts of the drawing that are done. If you use charcoal avoid blending it with a stump or rag or it will muddy the paper and not allow the paper to show through. I never blend my drawings but rather use small hatching marks to lay value down. Make sure to keep the points of your charcoal or pencils long and sharp to get the best hatching tones.