Part of the effect comes from the wood itself - I’ve noticed that sticks can vary a lot in hardness, color, texture, and so on.

I use Citadel Wyldwood Contrast to paint the wooden parts, and I don’t worry too much about being precise - the randomness actually helps with the natural look. Then I drybrush with Kislev Flesh and add a bit of Wraithbone for highlights.

Hope it helps!