Creating The Surface

Creating the surface of the face is quite simple at this stage. Using the line tool to go over the red quads, with the snap option turned on to make it easier for each quad to join to the last.

Whilst creating all the quads in 3D, I found it useful to make the quads see-through via the options in object properties, this allowed me to copy directly from the image behind. I also turned 'edged faces' on within the view port properties.
With the front of the face completed filled in I selected one quad and converted it to a polygon, which gives the quad a surface.
With the polygon selected I clicked Attach under the edit geometry panel on the right. Clicking 'All' in the dialogue box selects everything within the scene, then by control clicking the plane objects which represent the photos I could then attach all the other quads together, turning the quads into polygons and creating a flat surface of my face.

The next stage is to select the vertex which is in the top right and then control click each vertex going vertically down, so each vertex on the furthest right, where the middle of the face is, is selected. Under the edit geometry panel, clicking align X will put each of the verticies selected into a vertical line. This will make it easier later on when mirroring the face to create the right side.

Now I changed my view ports so I could see my front and side views. With all the vertical verticies down the middle still selected I pulled them out along the side view and moved each vertex into place along the shape of my face.

I found this part of the modeling process to be the most time consuming and most intricate. Having never created a face in 3D before, I spent a lot of time focusing and trying to get each vertex in the right position in regards to the front and side views. Creating the shape of the nose and the eye was particularly difficult as there is a lot of overlapping polygons and delicate positioning.

Once I had finished tweaking the basic shape of the face I could apply a turbo smooth modifier to smooth out the shape. At first I wasn't satisfied with the shape so I spent more time tweaking verticies until I was happier.