What to wear.

One of the most important things in the north is dressing correctly. You must protect every part of your body exposed to the air — otherwise it can lead to very serious health problems.

Most northern countries heat with electricity; every indoor space is warm, and you'll have no trouble staying warm. But when it comes to going outside, your first line of warmth is your clothing — and your car, if you have one.

Harsh winters are common back home too; we see days of sub-zero temperatures and biting frosts. Thick boots, the glove-scarf-hat trio and heavy cardigans usually win the day for us. But back home our time outdoors in extreme cold is short. In the north, especially while watching the northern lights, you may have to stand outside for hours with very little movement. Watching the lights dance, you won't want to quit even as your feet and hands begin to freeze. That's why you have to take a different approach; choose clothing that keeps you warm without making you sweat.

Hands and feet — the first to chill.

By its nature the human body chills fastest at the hands and feet. Warming the hands back up is easy, but the same isn't true of the feet: feet that begin to freeze usually won't warm up until you move somewhere warmer. So the right footwear choice matters greatly.

Be sure to choose a waterproof, windproof boot that doesn't make you sweat. Waterproofing comes in levels; stay away from the low ones. A boot that wraps your foot well, preferably covering the ankle, with a high, thick sole is ideal — but it must also be light, or it becomes a burden over the trip. Look not at the brand but at whether the model is genuinely effective against extreme cold; research user reviews about whether it works at −10, −20 degrees. As someone who tried boots from two different brands and still hasn't found what I'm after, I'll say it: one alternative is to buy a suitable boot in the country you're visiting.

Most boots slip on ice. You can try separate chains slipped over the sole (crampons) or a pointed walking pole. Don't drive with the chains on; most businesses will also ask you to take them off on the way in.

Socks.

Choose thermal socks that don't make your feet sweat; wear two pairs as conditions require. But remember: socks are only extra protection. If your boot lets water in, even ten socks one over another won't help — the chill carries on at a distressing level, and you'll only warm up indoors or in the car. Carry spare socks throughout the trip, and a spare pair of shoes if you can.

Layers — from base layer to coat.

The legs don't chill as primarily as the feet; an insulated, waterproof, windproof pair of trousers that doesn't restrict movement is enough. Base-layer bottoms and tops help greatly to hold your body heat. On top, wear a thermal fleece over the base layer, and over the fleece a mountain/outdoor coat made specially for winter: it should insulate, keep out water and wind, and breathe to prevent sweating.

Over the fleece you could also choose a soft shell jacket — thinner and lighter than the coat but with high wind resistance. Still, while waiting for the northern lights at night a soft shell may not be enough — always keep your coat with you. Ski clothing is suitable too, as long as it doesn't let the cold through while you wait motionless for a long time.

The day-and-night formula.

Touring the Arctic by day and by night are two different experiences. If you'll drive around, stopping here and there to take photos, you need a formula that won't leave you cold outside but won't make you sweat once you're in the car. Tune it by trial and error against temperature, precipitation and wind: in extreme cold like −20, −30, pick the most effective clothing; at above 0 degrees, or −5, −10, test dressing less heavily.

Head, neck and face.

Especially while waiting at night a thermal hat is essential. I particularly recommend wearing a balaclava under the hat to protect the face; pulling the coat's hood over it is the most effective answer to wind and cold. Use a scarf in a way that won't make your neck and mouth sweat. As you breathe in and out through the balaclava the mouth area can grow damp; open it now and then to let it air.

Gloves.

Like the feet, the hands are among the first to chill. A glove must be utterly waterproof and give full protection against wind and cold. Thick doesn't mean protective — a thin fleece glove with thermal insulation is effective too. When you take a glove off to shoot at −20 and below, your hands freeze within seconds; so choose a model that can warm the hand again. Instead of a five-finger glove, choose two-part mittens where the thumb and the other four share one pocket — fingers warm far more easily when they're together. Avoid fingerless gloves; use a remote for the camera instead. Stay away from metal accessories; put your watch in a pocket rather than on your wrist, and your phone in an inner pocket.

Skin care and the sun.

However cold the air, if it's sunny the ice and snow are intensely burning. To protect your skin, always use a moisturiser and sunscreen. In the cold, hands crack quickly; if you take no precaution you may find them bleeding at every finger movement by the second day. Apply cream to your hands and face especially before bed. Sunglasses should be with you both while driving and walking; a heavily tinted pair cuts the white glare of the snow and rests the eye.

Finally: be sure to pack a spare of each — underwear, base layers, gloves, hat, shoes, trousers and fleeces.