The expense of a brand new mattress may be prohibitive for some but a fresh pillow can also make a world of difference. But you should definitely get the pillow that is right for how you sleep.
For side sleepers, try out AERIS Contour Pillow ($47). For stomach sleepers, check out the Bluewave Bedding Ultra Slim Gel-Infused Memory Foam Pillow ($43).
But my favorite pillow is the Beckham Hotel Gel.