Myself being an artist, I have to ask, how old are you and how much professional training do you have? If you're an adult already and you have no training, you're basically wasting your time learning how to draw. People who are professional artists have generally been drawing consistently since a very young age, and generally also get professional training to some degree (I, for example, have about 7 years of professional training). That's not to say that an adult can learn to draw adequately, and there are plenty of resources available to learn, but in order to create a quality cartoon, manga etc., you're going to want a someone with professional training. Visual art is, generally, something you either devote most of your life to, or don't do.