This is a beautiful, seemingly loose drawing. Actually only the inking is loose. The drawing underneath is very solid and knowledgeable. The first thing a young cartoonist sees in a good cartoonist's work is the final details, the style, the inking - the last superficial layer. Those things are important, but only if the basic drawing skills are there in the first place. Style can't happen without substance and skill first.
These tips are from an old cartooning course and it explains all that very clearly.