There is a particular kind of misery that comes from a blister on day three of a long distance walk. The scenery is glorious, the weather is behaving, and every step feels like a small act of punishment. The good news is that blisters are largely preventable, and when they do appear, a bit of swift, sensible treatment usually keeps you moving. Here is how to look after your feet when the miles start to add up.

Understand what you are up against

Blisters are not bad luck. They are the predictable result of three things working together: friction, moisture and heat. Your foot slides slightly inside the boot with every stride, the skin rubs against sock and lining, and the resulting shear force separates the upper layers of skin until fluid collects underneath.

Your feet also swell during a long day, sometimes by half a shoe size. Feet that fitted beautifully at the car park in the morning can be tight and crowded by mid-afternoon. Add a bit of rain, a river crossing or simple sweat, and you have created a warm, damp environment where skin softens and breaks down far more quickly.

Understanding this trio is useful, because it tells you where to aim your efforts: reduce the rubbing, control the moisture, and give your feet room to swell.

Deal with hot spots the moment you feel them

A hot spot is a blister that has not yet formed, and it is the single most useful warning your body gives you. It feels warm, tender and slightly raw. Stop and treat it. Two minutes now saves you two days of limping.

• Stop immediately, even if it feels fussy. Take off boot and sock and look at the area.
• Dry the skin thoroughly before applying anything. Tape sticks poorly to damp feet.
• Apply a hydrocolloid dressing or a piece of woven zinc oxide tape over the hot spot, smoothing it down so there are no wrinkles. Wrinkles create new pressure points.
• Consider a larger piece of tape than you think you need, with rounded corners or a border of softer tape, so the edges do not roll up as you walk.

If the skin is already blistered but intact, leave the roof of the blister alone. It is a sterile, protective dressing that your body made for free. Only lance a blister if it is so large and painful that you cannot walk, and if you do, use a clean needle at the edge, drain it, keep the skin in place and cover it properly.

Keep feet dry and change socks at breaks

Dry feet blister far less than wet ones. On a long walk, this means managing moisture actively rather than hoping for the best.

• Choose merino wool or synthetic socks that wick sweat away from the skin. Cotton holds water against your foot and is best left at home.
• Carry at least two spare pairs on a multi-day walk. Change them at lunch and again if your feet get wet.
• Air your feet whenever you stop for more than ten minutes. Boots and socks off, feet in the breeze, even on a chilly day.
• Wring out wet socks and rotate them if you are caught in persistent rain. A dry spare pair in a sealed bag is worth its weight in gold.
• Consider a thin liner sock under your main sock. Liners move the friction away from your skin and into the sock layers, where it does no harm.

Some walkers dust their feet with talc or apply a small amount of anti-chafe balm. Both can help, but neither is a substitute for dry socks and air time.

Get the fit right before you go

Most blisters are really a footwear problem. A boot that is too small squeezes; one that is too big lets your foot slide forward on descents, which is why so many blisters appear on toes and heels.

• Size up and allow roughly a thumb's width between your longest toe and the front of the boot.
• Try boots on in the afternoon, when your feet are already slightly swollen, and wear the socks you plan to walk in.
• Lace properly so your heel sits locked into the back of the boot. A good heel lock lacing pattern stops the forward slide on steep ground.
• Break boots in gradually with shorter walks before committing to a long distance route.

Look after your feet each evening

End-of-day care is where long distance walkers quietly win. Wash your feet, dry them carefully, especially between the toes, and let them breathe without socks for an hour. Check for new hot spots and treat anything tender before it has a chance to develop overnight.

Trim your toenails straight across and not too short. Moisturise dry, cracked skin, but keep cream away from the spaces between your toes, where dampness encourages problems. If a blister has formed, keep it clean and covered overnight with a fresh dressing.

Finally, be honest about pain. A blister that is infected, hot, swollen and streaked with redness needs proper medical attention, not another layer of tape. For everything else, a little patience and a well-stocked repair kit will carry you to the end of the trail with your feet in reasonable order.