I have found that I need to spend more time polishing the overall composition and timing of the film before I get too far into the specific drawings. This is how Richard Williams describes how to proceed in the Animator’s Survival Kit (Thank you, Jane!):
I am still working on the storyboard, layouts, thumbnails, and starting to do SOME keys. I don’t want to leave myself too little time for polishing the animation itself, but I really need to make sure I’ve got the main armature of the film firmed up before spending time drawing things that MAY have to get thrown out later if they don’t fit, drawings I might be so invested in that it woud be difficult to cut them and throw them out when they really might NEED to be.