You just do it. And keep doing it... keep learning different styles and look at all kinds of art.
Some people are just naturals.. and it's amazing to watch them. My father sketched his whole life. Made sense he was an architect/builder, and a painter (water, oils.. you name it) and also a tattoist.. He never stopped getting better... His father was a draftsman, but never did anything outside of work. I never understood that.
I was lucky to gain some of his skills, but never to the level he did. He could draw upside down to explain an idea to a client.. blew me away... I put together a binder of all his stuff last year.
One of the coolest things I remember was when he taught me perspective drawing. That opened up a whole world for me. I still sketch every day.
Some of his stuff.. Mine doesnt even compare...
