I usually go out at least twice a year in less than perfect weather. Just to practice this.
On this trip I was testing out a Sog Force. It had been raining lightly overnight and changed over to snow in the morning.
I place a rock on the ground to insulate the fire from moisture. Sweedish Army Steel
I scrounge around for dry pine needles. Leaves that may be blown into holes at the bottoms of trees and out of the weather. Birch bark cut up small and rubbed even smaller,
I'll cut some curls for secondary fuel, mostly from small dead branches hanging in other trees.
Took a few tries, but it caught,
And grew,
Add sticks, and be happy!
I agree with much above, cattails, thistles, and others. And rubbing everything seems to break down the fibres and help with combustion.
For non natural, I use common houshold twine. A 12" piece will start many fires and weighs nothing. Cut about an inch off the end. Seperate the three strands. Then pull each strand apart. And roll it in your hands. Then roll all three together, pull 'em apart, and do it again. This will usually light on the first strike.