A mattress is made up of several important features:

Coils
The inside is the most important part of a mattress when it comes to supporting the body.  The core of a mattress is made up of coils.  The number of coils should correspond with how much support a mattress gives.  That is, a mattress with 300 coils will provide less support than a mattress with 700 coils.  Generally speaking, the more support you want the more coils you should get.

Another point to consider is the coil gauge, or thickness.  This relates to the mattresses overall "feel".  The wire in coils comes in a range of thickness and as a rule, the lower the gauge number, the thicker and stiffer the wire and the firmer the mattress.  The higher the gauge, the thinner the wire and the softer the mattress.  Whether you want thicker or thinner coils is up to you, but a problem can arise when someone tries to sell you a mattress with a low coil count and heavy gauge wire as a firm mattress.  Such a product can quickly become lumpy because it simply doesn't have enough coils.

Box spring
The box spring is the foundation of your bed and will significantly increase the life of your mattress.  It is a common misconception that box springs are not an important part of the equation when buying a new bed.  While a mattress sitting on an old box spring might feel the same as a mattress sitting on a new box spring, the fact is that you can add up to 2/3 to the life of your mattress by using a new one.  Today's mattresses should last about 10 years.  A box spring can be a plain, fiberboard-covered wooden frame, a wooden frame containing heavy gauge springs or even a metal frame with springs.  A wood frame is only adequate if the wood is straight and free of cracks.  But remember that placing a mattress on top of a plain wooden frame can make the mattress seem stiffer than it actually is.  Corner guards are a good thing to look for on a box spring.  They protect the fabric and keep it from chafing against corners.

Ticking/Upholstery
Ticking is the mattresses outermost layer and affects your comfort level while awake.  It is usually made from polyester or a cotton-poly blend.  Some inexpensive mattresses are made with vinyl ticking, but these tend to sag before their time.  As you go up in price, ticking will have a more distinctive design.  Fancy mattresses have damask ticking woven right into the fabric (instead of just printed on top) and some even contain a bit of silk.  But The Shopping Bags see that as more of a marketing gimmick than anything else.  Look for stitching that is uniform and unbroken, as broken threads could allow fabric to loosen and pucker.  If you want to feel like you're sleeping on a feather bed while getting the support your body needs, look for a "pillow top" design.  If you want to feel like you're sleeping on a board, look for the thinnest upholstery.  Neither of these choices will lead to a poor night's sleep because the support on the inside is the same.

Middle Padding
Just below the top layer of the mattress lies middle padding, which is usually made of foam.  Look for a mattress with foam shaped like an egg carton (convoluted), rather than foam that is straight and flat. Convoluted foam helps to spread your weight over a wider surface area and should make sleeping more comfortable.  Watch out for foams that feel dry or crunchy to the touch - they won't spring back as readily.  In some mattresses, firmness varies from one area or side to another.

Insulation Padding
Insulation padding is the protective barrier around the coils, which keep you from feeling those metal springs while you sleep.  The most common insulators are made from coco pad, the fibrous matter from a coconut husk, and shoddy pad, pieces of fabric that have been glued together.  Coco pad makes a mattress stiffer.  Also look for a mattress with a plastic webbing between the insulation padding and the coils.  The webbing will keep the coils from chewing the pad above.

Handles
Handles can help you position your mattress properly on top of the box spring.  But most warranties don't cover broken handles, as they're not designed to hold the entire weight of the mattress.  Handles come in a few different designs.  The best are those that go through the sides of the mattress and are anchored to the springs.  The next best are fabric handles that are sewn vertically to the tape edging of the mattress.  And unfortunately the most common handle design is also the weakest - handles inserted through the fabric and clipped to a plastic strip.

Any efficient shopper knows the importance of shopping around - especially when it comes to buying big-ticket items.  But mattress manufacturers have made it almost impossible to compare prices from one store to another.  Small features like stitching and fabric colour will change between stores, so that retailers are not forced to match and beat a competitor's prices.  The retailers win and consumers lose.

Materials
There are mattresses filled with water, foam and air, but by far the most common are those with innersprings - named for their coiled steel springs sandwiched between layers of padding.  The padding is identical on the top and bottom so the mattress can be flipped.  The padding is made of polyurethane foam, polyester or cotton batting.  Mattresses have become much thicker in recent years, widening from about 7 inches thick to the current 9 to 15 inches.  Today's wider mattresses require fitted sheets that are made "deep pocketed," "high profile" or "high contour".

Brands
The best-known names in mattresses are Sealy, Serta and Simmons.  While there are dozens of other brands available, these three manufacturers account for about 3 out of every 4 mattresses sold.

Support
Mattresses come in a variety of soft, medium and hard firmnesses.  While testing various mattresses, remember that a quality mattress will gently provide support at all points of your body as well as keep your spine in the same position as good posture when standing up.  Your body should be able to relax with the spine supported in its natural curve.  Otherwise, your muscles will be working while you sleep and you'll wake up stiff and sore.

There are several sales tactics to be aware of when shopping for your new mattress.  Low-ball advertisements show mattresses for sale at low low prices.  But what the ads often don't tell you is that these mattresses often come from the manufacturer's inferior "promotional" line.  The idea is to get shoppers into the store and sell something more expensive.  The ads also make those "blow out" sales seem rare, but mattresses are always on sale somewhere and a consumer should never pay full price.  Also, price tags often list a fictitious "original" price to make the sale price seem even lower.  Remember that the discounted price is often negotiable too. 

Manufacturers tend to use a lot of confusing jargon, like premium, superpremium, ultrapremium or pillow soft, plush, cushion firm and superfirm.  These kinds of descriptors should generally be ignored. 

The only way to tell if a mattress is right for you is to take the "nap test".  Wear comfortable clothing and take your spouse along with you when shopping and spend at least ten minutes on any given mattress.  Compare comfort by lying in different positions, like on your side, back and stomach, especially if you sleep with a partner.

As we said earlier, mattress makers also give different names to very similar mattresses - where the only difference is in negligible features like fabric colour or stitching patterns - to make it impossible for consumers to shop and compare.  So what can you do to get around this problem?  The Shopping Bags suggest calling the manufacturer directly.  Ask them if mattress A at store B is really the same (or very similar) to mattress C at store D.  Some manufacturers will divulge this information.

Be aware of stores with 60 or 90-day trial policies.  Several retailers allow consumers to return the mattress they purchased within a specified period of time if they're not happy.   This can be good for new mattress owners who sleep on their decision only to find out that they made a purchasing error.  However, this can also mean that you might be buying a slightly used mattress.  Inquire as to whether another shopper has returned the mattress you receive.

Be wary of salespeople who push a particular brand.  From time to time, manufacturers offer financial incentives to retailers to move certain lines.  Try out several models across several different brand names.

When buying your mattress, buy the box spring too.  It will increase the life of your mattress and you'll get a better deal as mattresses and box springs are sold in sets.

If you want a larger bed - like a king size - but the size of your hallways won't allow the box spring to fit through (the mattress can be bent), inquire about a two-piece box spring.

And finally, know that spending more for your mattress gets you thicker padding, damask ticking, and perhaps a pillow top - a cushion on both sides of the mattress filled with foam, wool or silk.

Caring for your mattress will ensure it continues to deliver a good night's sleep for up to about 10 years.

Turn and Rotate
A brand new mattress must be turned and rotated every few weeks to even out corners.  After a few months it should again be rotated to even out wear and tear.  The box spring should be rotated too.

Cleaning
If tough stains occur, use a mild soap and cold water and rub gently.  But generally speaking, a vacuum is the only recommended method of cleaning a mattress. 

Allergies and mattresses
Mattresses are prime breeding grounds for dust mites – microscopic bugs that live and reproduce in your bed.  (They love warm, dark places and they feed off things like mould and skin cells. Yuck!)  Dust mites release fecal matter that can build up and cause allergic reactions in some people.  Allergists say some mattresses hold up to 20% of their weight in this fecal matter.  

One way to prevent this fecal build-up is to prevent mites from entering your mattress in the first place.  Special dust mite covers can be purchased and placed over your mattress and pillows.  For the most effective protection against mites, the covers need to be placed on a new mattress, thus preventing mites from ever getting in.  A new dust mite cover on an old mattress won’t do much good as there is no way of getting rid of the fecal matter once it’s in there. 

If you have a tendency to allergic reactions it is recommended that sheets, pajamas and anything else that comes into contact with your mattress be washed on a weekly basis in hot water.