Here’s how you do it … start with a lateral neck stretch: Tilt your head to one side. Let’s stretch the left for example; tilt your right ear toward your right shoulder. You will feel the stretch.
Now, tilt your head slightly forward as well as laterally and you’ll feel the stretch more in the posterior neck. It’ll hit more rear traps, occipitals and paraspinal fibers.
Next, while laterally bending the neck, extend your neck back. Now you’ll stretch the SCM and scalenes. These muscles attach in the front of the neck which is why extending the head will stretch them. The opposite is true for muscles in just the back of the neck; flexing forward will stretch those muscles more.
Lastly, while laterally bending, flexing the neck forward or back, you can also turn your head. Looking towards or away from the right shoulder will also vary the stretches slightly, hitting slightly different neck muscle fibers.
Like other stretches, hold for 10-20 seconds in one position then move on to the next stretch. You can also stretch the other side. Stretch to tolerance, until you feel a good stretch. If anything causes pain or discomfort stop immediately. Using heat before or after stretching may help loosen and relax the muscles.