How do cartoon artists make their drawings come out so nice?

I want to know, what programs do they use? How do they take an image they drew in real life, and put it on the computer, and make it come out the way it does? If I tried to do that, It would look bad, the lines would be thick or gross or something, and the colors would be splotched, etc. So how does it come out clean?Any artist want to give tips?