Matt Jones outlining the importance of reportage.

You have to be familiar with architecture, landscape and the human form from every angle to be able to draw storyboards or animate traditionally. 

That's where maintaining a sketchbook comes in; to help build that repository of observation. I find once you draw something it sticks in the brain. The larger your mental library is the easier it'll be to draw whatever is required.

Classical life drawing is a fundamental requirement also- the ability to really observe and draw the human form is a discipline that seems to be dying out. 

To complement this quick 'gesture' studies are essential too- to capture a fleeting pose or attitude in seconds is good practice for doing the same in a storyboard or animation drawing. 

                                                                                                         Matt Jones