Pillows are another bed element you really need to be vigilant about replacing if you want to have your best nights of sleep, because inadequate support or allergens can really wreck your night. You should replace pillows every couple of years and regularly wash them, because after two years, one-third of your pillow's weight contains dead skin, bugs, dust mites, and their droppings. It's hard to get cosy when you remember that, so keep 'em clean.
Also, softer isn't necessarily better when it comes to pillows. The most important factor in pillow selection is that you have the right kind of support. Some people love feather pillows, but I personally lean toward foam pillows for firm neck support. If you keep waking up with a sore one, and you know it's not your mattress, experiment with different kinds of pillows.