Next we'll convert it from a primitive to an editable poly mesh. Right-Click on the word Plane in the modifier stack and you'll see a menu appear. Choose Editable Poly. This will change the modifier stack. You will loose the option to automatically add more virticle or horizontal segments, however you can add them manually now and will have control over individual vertexes, etc
Click on the little + button in front of Editable Poly and the sub-object selection options will appear. Select Polygon.
Select one half of the polygons and delete them!
Now click on the drop-down menu "Modifier List" and go way to the bottom and find the modifier called "Symmetry".
The parameters in Symmetry are very simple. Choose the Mirror Axis, in this case it should be X. If you see nothing, check the Flip options. Now it should look just like it did before - squares on both sides of the face. The difference is that now, any changes you make to the left side of the face will automatically happen to the right.
Click back down onto Editable Poly... ah! the other side of the plane disapeared again! No worries. There are several buttons directly under the modifier stack, one of them is "Show End result Toggle On/Off". If you click on this button, even if you're working at the bottom of the stack in the editable poly modifier, it'll show the end result with all of the other modifiers applied to it.
If you're aiming for high poly modeling, a great way to work is to apply a Mesh Smooth modifier to the end of the stack, but work in low poly. You can see how the model will look with the high poly end result, but still have the ease of working with fewer vertices and edges that comes with low-poly modeling.
Start move some vertices around to match the edge loops we're aiming for. Right now we're only working in one dimention, so it's still just a flat plane, but later on, we'll start pushing in and outwards and giving depth to the face.
Okay, so 6 edges isn't enough to get much done is it? You want to add some more edges in and it's pretty easy. There are several ways to add in more geometry. One is to connect selected edges, another is to cut edges. Right now we're in vertex sub-object mode, but we need to be in Edge mode, so select it from the modifier stack.
Select and edge and click the button that says "Ring". It selected all of the ledges paralell to it in a row! If you click the button that says Connect, it'll create edges going along the center of all of those edges. If you select an edge and click on the button the says "Loop" it'll select all of the edges in a straing line. These selection tools are quick and easy ways to select groups of edges. You can also do it manually. Click on an edge and hold down the Control key as you click on additional edges. If you select a group of edges and click Connect, it'll create new edges connecting all of the selected edges.
Another way to create new edges is with "Cut". If you click and drag on a blank space around all of the buttons in here (for example, click and drag on the empty grey area under the Ring button) you can scroll up and down in the options area. (there's a lot more than you see at first!).
Down a little bit, under Edit Geometry, you'll find a button called Cut. Click the button and try clicking around the plane. It'll create edges as you cut. Add edges, go into vertex mode, move around some vertices, and try to match the loop guide.
If you need to remove an edge, click on it and click the Remove button. Removing an edge leaves a verticie behind, and you have to remove any extra verticies too. If you remove a loop of edges and then go into vertex mode, you'll see a string of verticies were the edges were. Select the verticies and click the remove button to remove them.
Not only can you connect edges to create new edges, you can connect verticies as well. Select two verties that are diagnol from each other and click the connect button. It'll create an edge between them.
This is what I've got at this point
I pretty much just followed the image reference. I added a bit more around the nose because I know they'll be nessecary in a moment. The nose is a hard area to prepare for, it's one of those things that I tackle mostly when I've got depth to the face already and working in perspective view.
So lets move into the perspective view and see what we've got so far! Press the "P" button, or click on the viewport toggle button in the bottom-right of the screen. Then click in the perspective viewport and click the toggle button again. Either way, you should end up with the perspective viewport, full-size on the screen. Now you can rotate around the plane and look it over
If you do not see the lines you've cut into the plane, in perspective view, press the F4 key on your keyboard. It'll toggle between showing the lines and not showing them. If all you see is a wireframe, and not a shaded view, press the F3 button. It'll toggle between wireframe and shaded view.
Okay, so all that work, and all we've got is a plane. This next part is the hard one. It takes lots of time and a lot of little fixes to get the depth right.
So lets switch back to the 4-way view. Press the viewport toggle button once so you see all 4 views at once. In the side view, select all of the verticies and move them forward so that they're at the tip of the nose