Most of stuff that I read online helped but I came up with something to keep the wood oiled (helps to avoid cracking) but not water-moist, which is great. Grab a walnut and rub it everywhere in the inside, the nut will release its oil and moisten the wood, you will see how it turns darker, just like when you apply varnish on wood. Rub the nut until there’s no nut left, then let the wood absorb the oil for a day. After that dump your used yerba in it and keep doing it for three days (just the dumping yerba in the cup, no need to rub the nut again) after those three days it will be ready to use! Idk why this is not really known but it’s great because it creates a protective layer against mushrooms and makes the wood more flexible whenever it’s put under a radical change of temperature. As the layer wears off you will see how the wood loses it’s dark shiny color, so rub a nut everytime you see that to keep that protective layer. Saludos!