There are a ton of art drawing books and alot of them are bad. I would take up life drawing. That's the key. You can't learn to draw from an art book, you only learn to copy a style. Learn the fundamentals by taking a life drawing course, in real life or on youtube. Whether it's for comics, animation, 3d modeling... you first need to learn how to see, before you can learn how to copy a writer's art style.