1. If you sleep on your back, choose a rounded pillow to support the natural curve of your neck, with a flatter pillow cushioning your head. This can be achieved by tucking a small neck roll into the pillowcase of a flatter, softer pillow, or by using a special pillow that has a built-in neck support with an indentation for the head to rest in.
2. Or try using a feather pillow, which easily conforms to the shape of the neck. Feather pillows will collapse over time, however, and should be replaced every year or so.
3. Or use a traditionally shaped pillow with “memory foam” that conforms to the contour of your head and neck. Some cervical pillows are also made with memory foam. Manufacturers of memory-foam pillows claim they help foster proper spinal alignment.
4. Avoid using too high or stiff a pillow, which keeps the neck flexed overnight and can result in morning pain and stiffness.
5. If you sleep on your side, keep your spine straight by using a pillow that is higher under your neck than your head.
6. When you are riding in a plane, train, or car, or even just reclining to watch TV, a horseshoe-shaped pillow can support your neck and prevent your head from dropping to one side if you doze. If the pillow is too large behind the neck, however, it will force your head forward.
7. Sleeping on your stomach is tough on your spine, because the back is arched and your neck is turned to the side. [Source HealthBeat]