On those days when your tresses are just a little too tousled, it's easy to pull them into a pony tail and blame the hair gods. But next time you start to curse your crazy locks remember this: You have more control over your hair than you think!

If you shampoo your hair more than two or three times a week, you might be stripping out frizz-taming, shine-producing moisture. The result? Styles that fall flat fast.

How often should you shampoo? There's no magic number, says John Masters, owner of the New York City salon John Masters Organics. For curly or frizzy hair or a dry scalp, he recommends shampooing once every few weeks (yes, really), as long as you wet it and use conditioner to lift grime when it starts looking messy. Oily hair requires more washings, from three times a week up to daily.

Experts agree that most people simply use too much shampoo, which has a tendency to dry out your hair and cause extra tangles.

To prevent overdoing it, apply just a quarter-size dollop to the scalp and massage it in. On days when you can skip the washing, take advice from New York City-based stylist Eva Scrivo: "Touch up the front and crown of the head by misting a little water on each section, following up with a blow dryer."

A nutrient deficiency is the most common cause for life-less looking hair. Eating a balanced diet supports your hair, while using nutrient-rich hair-care products, especially those with the antioxidant vitamins A, C, and E, keeps damaging factors like pollution, poor water quality, and sun exposure from causing problems.

Another tactic to try: Products containing organic herbs and essential oils will stimulate circulation in the scalp and balance key oil production that can add sheen and volume to your hair.

Unhealthy dyes can leave your hair color flat and strands brittle. Used in many salon and home hair dyes, the ingredients ammonia and PPD (p-Phenylenediamine) expand the hair shaft and help color stick. By manipulating your hair's natural structure, dyes make it tough to maintain a shiny, healthy-looking 'do.

But a healthier dye job is possible. Health-food stores stock many ammonia-free/low-PPD hair color, while an increasing number of salons offer vegetable-based dyes. Following color application, stylists recommend applying a nourishing hair mask to help smooth and coat the hair cuticle and give it additional shine and resilience.

Protect your hair from turning brassy, streaky and frizzy by simply shading your strands any time you're in the sun for extended periods of time. Even when the temperature is hovering around freezing, sun damage can still wreak havoc on your tresses many months later.

Too much UV exposure weakens the hair's keratin (protein) and causes melanin oxidation, or discoloration, resulting in brassiness. Although chemical SPF products help mitigate the damage year-round, a sun hat or a nourishing hair pomade with beeswax, plant butters, natural oils, and/or vitamins will act as a physical barrier between hair and the sun.

We've all had those days when your roots feel greasier than the floor of a car garage. Not brushing enough is usually the cause. In the days before women had easy access to thousands of hair-care products, a nightly hair-brushing session was de rigueur. As it turns out, our forebears were on to something: Brushing helps move oil from hair's roots to its ends, conditioning strands evenly, protecting them, and eliminating the tangles that can lead to breakage down the road.

"When you have skin and hair challenges, the body is letting you know it needs help," says Lisa Petty, a holistic nutritionist and author of "Living Beauty." Boost your intake of these nutrients to heal damaged hair:

Protein
Fortifies the hair and promotes growth. Food sources: beans, dairy products, eggs, fish, meat, and poultry.

Iron
Oxygenates blood and boosts circulation in the scalp. Food sources: asparagus, dried fruit, egg yolks, legumes, red meat, dark leafy greens, and whole grains.

Omega-3s
Prevent dryness and add moisture. Food sources: flaxseeds, sardines, soybeans, walnuts, and wild salmon.

Silica
Strengthens the hair cuticle, boosting strands' elasticity. Food sources: cabbage, celery, and steel-cut oats.

The scalp can actually give you clues about how to care for your hair. If it's dry, your hair is probably dry, too, and more likely to break. An oily scalp pretty much guarantees that your roots will fall flat by midday. Tend to your scalp, and your hair will feel the extra TLC, too.

Choose a shampoo that matches your scalp type and a conditioner for your ends, whether they're fine, curly, colored, dry, or damaged. Apply conditioner a few inches from your scalp and work down.

"You don't want it on the skin because even after rinsing, some oils, waxes, or silicones will stay behind, and that moist environment can lead to fungal overgrowth," says Zoe Diana Draelos, M.D., consulting professor in the department of dermatology at Duke University School of Medicine in Durham, North Carolina.

"Most people don't shampoo thoroughly," says New York City salon owner and hair stylist Valery Joseph. Often, he says, we skim over our hair's roots but don't actually clean the scalp itself. So oils, dirt, and styling products keep building up, causing oiliness, dullness, and itching.

Joseph advises dedicating three minutes to lathering up. Then go ahead and give your scalp a rub when you're out of the shower. Besides being a tension-buster, it'll exfoliate the surface and leave hair fuller and shinier, says Marc Zollicoffer, a global educator for Aveda.

Ongoing extreme stress can also thin your hair. But the good news? Hair loss due to acute stress is almost completely reversible.

"Each hair you see in the drain is being replaced by a new one," says David Bank, M.D., a dermatologist in Mount Kisco, New York. "It's a one-for-one swap." If you're experiencing ongoing stress, it may help your hair if you add yoga, mindfulness meditation, or other relaxation techniques to your daily routine.

"When you use a lot of heavy styling products -- such as gels, waxes, and hair sprays -- it can build up on the hair, making it look dull and feel as if there's a residue that won't wash off," says Elaine Mitchell, senior creative director at Sassoon Salon New York City Uptown.

Switching from your usual shampoo to a clarifying version can help. These deep-cleaning formulas strip away buildup that accrues from hair products and environmental pollutants.

Although these shampoos do a great job of ridding hair of unwanted residue, they need to be used sparingly since they can deplete essential oils and cause hair dye to fade. A hair detox once every couple of weeks is usually all that's needed.