A small number of items genuinely determine whether a trip is comfortable and safe. Most of the rest is interchangeable, and the industry does not present it that way.
Footwear, where fit beats everything
Trail shoes for most trail walking — lighter, faster drying, fewer blisters.
Boots where you need ankle support under a heavy pack, on rough or loose terrain, or where water resistance matters.
Neither is universally right, and the fit matters far more than the category. Feet swell over a long day; buy with that in mind and walk in them before the trip.
Socks matter more than most people credit — wool or synthetic, never cotton, and a spare pair kept dry.
Layers, which is a system rather than items
Base layer — wool or synthetic, moving moisture away from skin. Cotton is the failure mode: it holds water and cools you.
Mid layer — fleece or a light insulated piece, trapping air.
Shell — waterproof and windproof.
The point of the system is adjusting before you get too hot or too cold rather than after. Most discomfort outdoors is a failure to stop and change layers.
Waterproofs, where the marketing is thickest
Beyond a moderate hydrostatic head figure, the practical difference between jackets is breathability, durability and features rather than waterproofness.
A good hood — adjustable, with a stiffened peak, that turns with your head — matters more than the membrane brand.
Reproofing an old jacket with a wash-in treatment frequently restores most of its performance, and is what people should do before replacing it.
Waterproof trousers are more useful than they look and are the first thing people leave behind.
Sleeping, where the ratings mislead
European-rated bags list comfort, limit and extreme temperatures.
Only the comfort figure is a realistic sleeping temperature. The limit assumes a curled position and the extreme is a survival figure, not a usable one.
Buy on comfort.
The mat matters as much as the bag. Insulation from the ground is measured in R-value, and a good bag on a thin mat is cold. This is the most commonly underspent item.
The pack
Fit to your back length, not your height, and load it in a shop before buying.
The hip belt should carry most of the weight; shoulders steady it.
Capacity: 30–40 litres for hut-to-hut, 50–65 for camping, more only for expeditions or winter.
What does not matter much
Brand. Mid-range gear from established makers performs close to premium for most uses.
Ultralight everything. Worth it for through-hikers, marginal for a week.
Technical fabrics for base layers beyond wool or basic synthetic.
Gadgets — most electronic devices are a battery to manage.
What is worth carrying regardless
A head torch, always, even on a day walk.
A paper map and compass, and the ability to use them, since phones fail in cold and wet.
A small first aid kit with blister treatment, which is the injury you will actually have.
An emergency shelter or bivvy bag on mountain days — light, cheap, and the difference between an incident and an emergency.
More water than you expect, and a way to treat more.
The general rule
Spend on footwear, the mat, the shell and the pack. Borrow or buy cheap for the rest, and replace individual items as you learn what actually fails you.