Whatever you have an affinity for. I used birch.
When you carve the rune, sound out the name of the rune, focus on the sound of the rune, then paint them.
I thought the traditional wood was Beech Tree. In German this translates to Buch (Beech) and from there you get ‘Buchstaben’ ( = Letters) and Bücher (Books)
The literal translation of Buchstaben is ‘Book Sticks’
But I am not German so I might be speculating here.
I bought a set of semi-precious gemstone Runes with gold paint ages ago because I liked the way they looked and I don’t use Runes for divination that often, and could not see myself sourcing wood, preparing it, etc. (I have to add I do have some wooden Runes but I used a slightly different configuration, and don’t use them much for divination.)
I think if working with Rune drawing is your PATH, the time and inner work following the Havamal guidance is worthwhile, but I mostly use them for spell workings and it wouldn’t have been economical, time-wise. Also it seems almost a crime to lovingly craft a tool that barely sees use.
For that reason, if you’re considering the gemstone Runes, look for the one you think is most attractive or maybe find out which stone if found in both Northern Europe and Africa, to get “the best of both worlds”?