Sometimes, you start with the drawing and then the gag comes to you in the middle of it. That is when you start working on the solution of the gag, which is composition, placing, equilibrium, and character design.
It is a good thing for an uneducated man to read books of quotations. Bartlett's Familiar Quotations is an admirable work, and I studied it intently. The quotations when engraved upon the memory give you good thoughts. They also make you anxious to read the authors and look for more.