1: Be Careful With Shampoo
Shampooing too often is one of the most common causes of dry hair. Many people believe that squeaky-clean hair is healthy hair, so they wash it one or more times every day. But shampoos often contain harsh cleaning agents that can strip away your hair’s natural oils, which help hold in moisture. On the other hand, a gentle shampoo will stimulate the oil glands, so you probably shouldn’t go longer than three days without a good lather.
The ideal shampoos for dry hair have a pH of between 4.5 and 6.7, but here’s a good rule of thumb: Don’t use any hair cleanser that you wouldn’t put on your face. Some people recommend baby shampoos, but their pH is usually far too high; such alkaline shampoos dry out the hair. Acidic shampoos are better for your hair.
2: Be Kind to Your Hair
Dry hair is the most fragile type of hair and is subject to breakage, so it must be handled with care. When lathering, be gentle. Avoid any pulling or yanking on your hair in any way, which strains the hair shafts. Don’t scrub with your fingernails, which can not only break the hair but irritate your scalp. Work up a lather using your fingertips, instead. Gently rubbing your scalp with your fingertips will also stimulate the oil glands.
3: Pour on the Conditioner
Strawlike hair needs conditioning. Look for products that contain little or no alcohol, which will dry out hair even more. Reading labels will help, but it might be simpler just to take a whiff before you buy: Conditioners with little or no fragrance tend to be low in alcohol or contain none at all. If your hair is really dry, consider using an overnight conditioner, which you apply before going to bed (you sleep wearing a shower cap) and rinse off in the morning.
4: Use Hot Oil
Hair-care professionals often recommend hot-oil treatments to repair dry, damaged hair. Over-the-counter hot-oil products are available that you heat and place on the hair for 5 to 20 minutes (according to package instructions). Wear a plastic bag or shower cap over your hair while the hot oil is on, then wash the hair thoroughly with a gentle shampoo.
5: Brush Less
Despite what you may have heard, too much brushing can actually fracture the hair, causing it to fall out. Fragile, dry hair is even more vulnerable to excessive brushing. Always brush hair gently and never when it is wet (use a comb, carefully, when hair is wet). The type of hairbrush you use is important, too. Boar-bristle brushes or "vent" brushes are good choices, since their rubberized tips don’t pull the hair excessively.
6: Hold the Heat
Using hot combs, hot rollers, and blow-dryers is asking for dry hair. Hot rollers are the worst because they stretch the hair while the heat shrinks it. Hot combs also tend to stretch the hair while exposing it to heat. If you must use artificial heat, keep your blow-dryer on a low setting and avoid pulling or stretching the hair while drying
7: Pace Your Hair Treatments
If you perm on Tuesday, dye your hair on Thursday, and put it in hot rollers on Saturday, your hair is destined to be dry and damaged. You don’t have to abandon styling practices such as dyes, permanent waves, or hair straightening if you have dry hair. Just keep in mind that it’s important to space those treatments out as much as possible.
8: Try Vinegar
There are several ways you can help your dry hair with vinegar. Vinegar is a great conditioner and can improve cleanliness and shine. Just add 1 tablespoon vinegar to your hair as you rinse it. Keep a travel-size plastic bottle of vinegar in your shower for this purpose, and take one when you travel, too. Since dandruff can make your hair look dull, use vinegar to make dandruff disappear. Massage full-strength vinegar into your scalp several times a week before you shampoo. Or, a brief soak in vinegar and water before you shampoo can help control dandruff as well as remove the dulling buildup from sprays, shampoos, and conditioners.
Add 1/4 cup apple cider vinegar to a small basin of water and drape your hair into it. As an alternative, you can put the concoction in a spray bottle and apply it to your hair. A conditioner that controls dandruff and gives your hair a healthy shine can be made by mixing 2 cups water and 1/2 cup vinegar. Apply the conditioner after rinsing out your shampoo, and let it stay on your hair for a few minutes before rinsing thoroughly with water. If you need a stronger treatment for dandruff control, use this same method, but keep the rinse on your hair for 1 hour, covered with a shower cap. Then rinse it out. This vinegar rinse will also help control frizziness in dry or damaged hair.
9: Use Eggs for Shine
To clean hair and give it a super shine, whip an egg into tepid water (not too hot or you’ll be dealing with a poached egg), then lather it into your hair. Rinse it out with tepid water or that egg will poach right on top of your head. To deep-treat damaged hair, give it a healthy sheen, and cure dryness right down to the roots, use this pre-shampoo conditioning treatment: Mix together 3 eggs, 2 tablespoons olive oil or safflower oil, and 1 teaspoon vinegar. Apply it to your tresses, cover with a plastic cap, and leave it on for 30 minutes. Then shampoo as usual.
10: Look in the Cupboard
Nuts and seeds. Try snacking on some seeds and nuts. They contain essential fatty acids that can pop that sheen right back into your hair.
Avocado and banana. Mash a little overripe banana and avocado together, spread in your hair, and leave it there for up to an hour. Then rinse with warm water.
Beer. After your shampoo, rinse your hair with a little beer. This can help restore shine.
Mayonnaise. You’ll need the full-fat kind, not a diet or low-fat version. Slather 1 tablespoon or so onto your hair, rub it in down to your scalp, then cover with a plastic cap and wait about 30 minutes. Rinse it out thoroughly or you’ll be craving tuna salad the rest of the day.
Oil. Rub a little oil into your scalp. Olive oil works well, as does coconut oil. After you rub it on, cover your hair with a cap and leave it on overnight, then shampoo and rinse the oil out in the morning
Source: Read this in howstuffworks.com