A finished sketchbook! A new begining!

I finished my sketch book!  
Its always a good feeling to move on to a new one.  This one turned out to be more of a "quick painting book", but I had a lot of fun learning more about values and trying to render lighting.

I think next I need to work on life drawing.  I know I am always saying this, but drawing from life is the source of great cartoons!  How can you know how to stylize well if you don't have anything to stylize from?

How do you keep yourself in balance between drawing from life and drawing from your head?  Let me know!