One thing to think about when learning how to draw figures is to give your figure drawings context by including in your drawing some element of the figure’s surroundings.
Spending a little time making some marks to suggest the model’s surroundings means your drawn figure will not be floating in white space. The surroundings need not be painstakingly accurate, but simply enough to help the viewer to makes sense of the attitude of the figure, and they way their limbs and body are sitting.
For example, drawing the cushions that a reclining model’s head rests on helps the viewer to make sense of the attitude of the figure’s head in the drawing. Showing the chair a model is sitting on gives context, and explains to the viewer how the pose can be just so.
The marks that suggest the surface this woman is reclining on help to make sense of the pose for the viewer.
Another element of the scene that will help to give context is shadow. Wherever you have a light source, you will see a shadow. You will see shadows every day, everywhere, and so it is easy to become so used to them that you no longer register them. Don’t forget this when you are thinking about how to draw figures. Try not to take the shadows for granted, and incorporate them into your drawing.
The example picture is a quick drawing from a life-drawing class. I think the bold shadow of the figure gives the picture a depth it would not otherwise have.
There will be both the shadows cast by the figure on the surroundings, but there will also be shadows on the figure itself. For example an arm nearer to a light source might cast a shadow on the figures torso. Capturing the shadow helps you to capture the way light fall on the figure and so helps to give it context and ground it in reality.
The two main parts to a shadow. First, the umbra the darkest part, which is completely hidden from the light source. Then, the penumbra, a lighter part of the shadow, where the surface is only partially hidden from the light source.