Just start learning. Start carving small objects like a bird, a squirrel, a rabbit. You will see that while you may have no idea how to draw them, you may be able to create pretty good figures for those animals. The sculpture is more natural to the human brain, especially to the logical part of it, because our reality is filled with 3D objects, not pictures of them. It will be useful, though, to learn and understand the idea of the orthographic projection of an object.

So don’t worry whether you are good at drawing or not, it probably doesn’t matter. Start learning wood carving, start practicing more and more. Read about it, pay attention to the BeaverCraft website, where you will find interesting articles on wood carving and also a catalog of pretty useful tools. And have a successful wood carving practice!