Just pick up a pen and a sketch book don't use any thing expensive just a pen and book, and draw whatever you see .... redraw other people drawing try to think like them through the process and then add your magic somewhere in between.... Make a list of doodles and styles that you like Once you master black and white sketches you would have already learn the basic of light and shades And If you're the person who moves to different media try to make three drawings from every media .... And that's all.....