How to draw is not too hard, what is hard is analyzing what you want to draw, I can not teach anyone to draw through a blog that would be silly, learning to draw is 90% looking and 10% marks on the paper.
Making marks on a piece of paper is the easy part, joining them together to make sense of them is what you are trying to achieve.
It really does not matter what style or genre you want to achieve the marks still have to be at the right angle, the right strength of dark and light. Shadows are darker on the whole but then there is detail in the shadows, ergo shadows are differing shades of dark and light.