If there is one fundamental to drawing that is often overlooked it is perspective. Everything we look at is based on where our eye level lies. This refers to the height at which our eyes observe an object. In the drawing on this blog, the picture is drawn as thought I am standing at the end of a hallway looking toward the double doors with my eye about the same height at the window in the door. When I took drawing lessons, we were told to lie on the floor face down and look around. What do we see? The floor, of course. But, if we look forward, we see the bottom of the door. As we look up, we see a different perspective of the walls, windows, and ceilings than we would if we were standing.
All of this shows me that I need to put a pencil in my hand, wrap my four fingers around it, hold it up between my thumb and those fingers. Then, as I extend my arm out in front of me, I can bring the top of the pencil up to my eye level and look at an object in the distance. Now, I can draw that object using proper perspective.