If you've ever envied a celebrity's gorgeous full locks, we hope you know by now they're probably extensions. It's not your fault if you don't roll out of bed with amazing beach waves. Extensions do more than add length; they also add volume. If you have hair that's at least 3 inches long, you can get extensions. You can have them braided, glued or woven in, or if you only want them super-temporarily, you can clip them in as well. And they come in all kinds of colors, so you can match your current hair color or add a highlighting or lowlighting effect.

What to look for

"A hairstyle can make or break your look," says stylist and hair extension specialist Cesare Safieh. Safieh cautions there are some important questions to ask when selecting extensions:

  • What are the extensions made from? Are they synthetic or 100 percent natural human hair? (Human hair is more expensive than synthetic counterparts.)
  • How will the extensions be applied and removed?
  • Can you choose from a variety of weights?

Safieh is a fan of a method of extensions known as Thermo Plastique, which involves a relatively gentle process that can be removed without damage to your hair. (He also adds that the micro bonding points are barely visible.) He says older methods, especially glue, are damaging. "Tracks (sewing) can be too heavy, and metal clips wear out and are hard to brush through."

"[The goal with] extensions is to have the most natural look you can achieve," says Tony Promiscuo, owner of Atlanta's Godiva Salon, who notes that while synthetic types are most plentiful, human hair is superior in its viability. (In addition, synthetic hair cannot typically be heated, so styling options are limited — meaning forget the blow-dryer and curling iron.)

"Individual strands allow a customized, more natural look," says celebrity hairstylist and salon owner Philip Pelusi of New York City's Tela salon. "You can play with the color or length and fill in spots that need it more than others. It's a more accurate way to get the desired look."

What to avoid in hair extensions

"The most important thing is to avoid extensions and pieces that are heavier than your own hair. If extensions are too heavy, they will damage and break off hair — so hair needs to be long and healthy enough to withstand the pressure," Pelusi points out.

More: The Best Antiaging Hair Products That Really Work

Ask about getting a variety of weights, because a single one may not work for everyone. In particular, extensions that do not match your hair are most likely to give you problems. Safieh recommends a type of extensions called Hairdreams, which offer a variety of weights or thicknesses to match your true hair — as well as the ability to preorder highlights and lowlights. Hairdreams last up to seven months and the hair can be reapplied, which also helps to decrease cumulative costs of new hair and removal.

Specialty methods have emerged from certain salons, such as the Goddess Loc, which has a silicon grip and plastic coating in order to avoid damaging your hair.

Next: How much are hair extensions?

A version of this article was originally published in July 2009.

How much are hair extensions?

The bad news: Hair extensions aren't cheap. Depending on how much you get, how you get them attached and the type/grade of hair you use, the cost can range from the hundreds to the thousands of dollars — and that's not including maintenance every six to eight weeks. Cheap clip-ins retail for around $50, whereas celebrities pay upward of $4,500 for extensions. You will also need to make an investment of time, usually four to six hours, for the initial setup.

The specialist who will apply your extensions may be called a hair designer, an extensionist or simply a hairdresser. No matter what title he or she uses, be sure they are experienced and have photos to prove it. Also, make sure you understand how they will be removed and how damage to your natural hair can be minimized. No one wants a bald spot.

More: 7 Insanely Easy (& Pretty) Hairstyles for Wet Hair

Is caring for your extensions going to give you a headache?

Do extensions require a great deal of upkeep and time commitment? Not really, says Pelusi. "People just need to keep an eye on them — almost like you would with color or anything else," he adds, suggesting you allow for an hour at the salon every six weeks.

Caring for your hair extensions

Different types of extensions require different care, so always make sure to follow instructions for your particular kind. Here are some specific tips to help you care for your extensions:

  • Human hair extensions can be treated as real hair, but more gently.
  • Use a special brush (often a loop brush) made just for extensions so you don't damage the new hair or the bond.
  • A gentle shampoo is recommended, and use cool water to help minimize tangles.
  • A light conditioner will help reduce tangling and keep your new hair supple.
  • Sleep with your hair in a ponytail or braid to avoid bed-head and knots.