When I am teaching how to build/make a fire, I tell people to look at and think about the branch of a tree.
We will use this fallen Birch as our example.
Next you want material about double the diameter
Finally we can now burn fuel of the diameter found at the base of the branch where it joins the trunk.
I am not of course suggesting that there needs to be a convenient branch available each time you make a fire, but looking at a branch gives you a guide to the size of material needed.For a brew fire you would probably only need material up to the size featured in picture three.
In the next post I will put these steps into practise.