Open Adobe Illustrator and choose File-Open. Select a photo of a face that you want to reproduce as a digital face. Open the photo and select File-Save As. Save your Illustrator file.
Click on the image menu and choose Adjustments-Posterize. Posterizing your image will break it down into basic color blocks. This will allow you to more easily trace around the general shapes and shades that make up your person's face. Check the preview box and choose a posterization level that best represents how detailed you want to make your final image.
Choose the New Layer icon in the layers palette to create a new layer. Name the layer "skin". Select the pencil tool and use it to trace around the skin of the face and neckline. If necessary, use the direct selection tool to reshape the face that you drew. Switch to the eyedropper tool and sample a color from the face of the original image. This will add the color to your new skin shape.
Create a new layer titled "hair" and proceed with the same steps to trace and color the hair area. The more detail you put into the shape of the hair, the more professional your digital face will look upon completion. Feel free to trace the hair over the top of the face where necessary, as some pieces of hair may overlap the face.
Turn off the Toggle Visibility icon (shaped like an eye) next to the "skin" layer. This will allow you to temporarily see the facial features of the original image and accurately trace them. Create layers for each feature of the face, such as "lips," "eyes" and "eyebrows". Once you have used the pencil tool to draw each element, the direct selection tool to alter your drawing, and the eyedropper tool to color each feature of the face, turn the "skin" layer back on by selecting the eyeball icon again. Rearrange the layers so that these layers sit above the "skin" layer but below the "hair" layer.
Toggle off the visibility of the "hair" layer to see the highlights in the hair. Look for highlights in the person's actual hair color or simply areas of hair that reflect more light in the photograph. Create a new layer called "hair highlights" and trace them with the pencil tool. Color them either by using the eyedropper tool or selecting a color a few shades lighter than the original hair color. Toggle the "hair" layer back on. Rearrange the layers so that the "hair highlights" layer is at the top.
Focus on the highlights of the skin by toggling off the "skin" layer. Create a new layer called "skin highlights" and trace them with the pencil tool. Color them in the same manner you used to color the hair highlights. Toggle the "skin" layer back on and place it directly above the "skin" layer.
Save your final image after you have completed each of the details. Be sure to toggle all layers back on at this point.