Decide what size mattress you want to purchase. Mattresses come in several sizes, including king, queen, full and twin, with king being the largest. This decision should be based on the size of your room, bed frame and the people who will be sleeping in the bed. If you're over six feet tall, for example, a twin mattress might not be long enough for you to stretch out comfortably while you sleep. Also, you need to have enough room to move around while you sleep; therefore, you should consider purchasing a king or queen size if you're sharing the mattress with your spouse or significant other.
Figure out if you want to buy a different type of mattress than your last purchase. The type is usually determined by the firmness of the mattress. If you're sleeping worse than you were when you first purchased your last mattress, it might be time for a change in firmness level. To determine the firmness level that's right for you, it's best to actually go into the store and test out different types of mattresses. This means actually lying down on the mattress and simulating your typical sleeping position. A good salesperson will insist that you do this.
Pay attention to the comfort scale of the mattresses you test out. Different mattress brands will have different methods for rating the comfort level of the mattress. A salesperson will be able to help you compare the different rating systems to find the comfort level that's right for you within a particular brand.
Rule out different types of mattresses as you try them out. Keep track of which types you like, and then try out several mattress brands that offer the firmness levels you prefer. If someone is going to be sharing the mattress with you, make sure you ask for his or her input. The mattress is the most used piece of furniture in your home and you want to make sure you and your partner are completely comfortable with your new mattress. If you have different support preferences, consider purchasing a mattress that has adjustable firmness levels for each side of the mattress.