Start by selecting a high-resolution reference photo of a portrait where all the details, highlights, and shadows can be clearly seen.
Begin lightly sketching out the basic elements of the face with Prismacolor Col-Erase pencils.
You may lightly shade in the shadowed areas to further map out the features and begin establishing contrast.
Use Prismacolor Premier markers to further establish values and color the face in. Lay down lighter colors first to establish values and gradually layer darker colors to build contrast.
When filling in the skin, use a very light color for the first layer (PM-12 was used here, but your color choice will differ depending on the skin tone of your portrait) and leave areas where there are bright highlights blank.
Begin adding details, starting with the most intricate parts of the face (eyes, nose, mouth) and ending with the larger areas of skin (forehead, cheeks, jaw).
Since the wider patches of skin cover more surface area, save building layers on these areas for last. You will need to work faster rather than slower to avoid visible marker streaks from allowing the markers too much drying time.
Layer Prismacolor Premier colored pencils over the marker, lightly laying down pigment and gradually building layers. Similar to the markers, start with a base of light colors and blend deeper and darker colors over top in shadowed areas to create contrast.
Once enough pigment is built up, apply a sharpened white colored pencil in circular motions to create highlights and texture around areas of the skin.
Continue to build contrast, blend, and add details as necessary.
Optional: use a spray fixative over the piece and add final details over top once it has dried.