Make the usual front and side view drawings.

Tip on positioning template drawings:

You can go into the map UV coordinates in the material editor, and adjust the UV [XY] positions on the plane, if one image is a little too high, etc.

Add projected lines for your splines in quads or 3 sided.

Set up the background art centered on World view.

Do one side in front view with Bezier curves ... adjust in side view and checking top and perspective as you go.

Or you can work in Smooth. If you want a smooth line, be sure to click and drag a little to activate the smoothing.

Drawing the splines

You can go linear vertex to vertex, then convert vertices to smooth, or, draw in smooth.

A good way to proceed is, select vertices in front view, then adjust depth position of the vertex in side view.

Put on the Surface modifier so you can see the model develop.

What about the mirroring and the center spline?

Build out the center splines and at the time of attaching the 2 sides, remove the duplicated segments and fuse the vertices.

Building out the Edge Loops

You can save time by shift/scaling and generating the outer loops quickly [for example, around the first eye spline] ... then adjust individual points.

Settings

Drag type to smooth

Right click properties of line = turn on vertex ticks

Convert to Editable Spline

Selection Rollout

Vertex Area Selection – ON

Selection radius to whatever you want to “grab” a cluster of vertices ...

This will make fused vertices move together.

You will see, you might need to turn this off if you need to pull a vertex away from a fuse cluster.

Weld coincident endpoints

Defaults threshold = 6.0

Set threshold to 0.0 if you are having problems with this

Create Line to add

Turn off start new shape

3D Snap

Endpoint – ON

Grid Points – OFF

Use Axis Constraints – OFF

Turn on and off 3D snap as needed.

Refine adds vertices; Create Line connects them

Change vertices to Smooth after creation

You can use Fuse just as well as snap. To fuse means to make coincident in spline modeling.

Connect can also be used between vertices.

You need to create only 3 or 4 sided shapes for the Surface modifier.

You can also use Refine with Connect selected to make vertices and splines as you go.

CrossInsert

Radius: 6.0

Cycle: Used to select different coincident vertices