Clothing is your immediate shelter protecting you from the environment
For clothing, remember the acronym C.O.L.D.E.R.
C = Clean
The less clean your clothes are, the less effective they are at providing insulation and sheltering you from your environment
O-L-D = avoid overheating, wear loose layers, and stay dry
Avoid overheating (“O”) refers to the prevention of sweating. When you sweat, it basically takes all the insulative properties out of your clothing.
Sweating is a bad thing, and loose layers (the “L”) help prevent that. Remove layers if you heat up, add layers if you become cold.
Then dry (“D”) is our goal, keep your clothing dry.
“E” = examine your clothing, look for any rips or tears“
“R” = repair
Use a four-layer clothing system, with C.O.L.D.E.R. Principle in mind:
1) An inner wicking layer against your body to wick away perspiration. That is your base layer, meant to prevent heat loss.
2) On top of that, wear an insulating layer. That could be fleece, wool, down, anything that will insulate and keep the heat close to your body.
3) Your third layer should be your durable layer. Example: a flannel shirt and Carhartt pants.
4) The last layer should be a windproof, waterproof layer, like a Gortex shell or a rain suit. That prevents heat loss from conduction. If you get wet, the colder water will sap the heat from you. It also prevents convection from the wind current.