Fire is important in cold weather, not only it provides a means to prepare food, it ables you to get warm and to melt snow and ice for water.
So lets go back to basics, fire needs Oxygen, heat and fuel which if mixed at the correct amounts will result in FIRE!!!
Tinder-Birch bark, tiny twigs dry pine branches are a great source (they must snap easily), cotton wool balls, lint from the tumble dryer at home also works well.
Kindling-Slightly larger pieces of wood. (add slowly once the tinder is alight)
A good supply of wood in varying sizes to build up from your kindling.
when the cold is an issue, making fire may be harder to start, one reason will be yourself. Cold hands and a waning patience are more likely to make fire lighting harder than anything else.
So remember good tinder and kindling are essential as well as prior preparation are key to the art of fire lighting.