After building lots and lots of workflows, I have created a simple process form that I use as a starting point for approaching workflows with Nintex. It helps keep me focused, gathering the right information, and thinking things through before I even touch a computer. This is about the business process, not the software, but will help.
This is great, Eric! I blogged about having a plan in mind before one endeavors down the path of building a shiny new Nintex workflow some time ago so I all I can say is well done! Plus, in lieu of using a cocktail napkin, I think giving folks a space to draw it out is immensely helpful.