Rachel describes her process of putting technical talks together:
This method of creating a talk is the one that I find gets me from blank page to finished slide deck most effectively.
She also acknowledges that many other processes are available.
If you are stuck, and your usual method isn’t working, don’t be afraid to try a different approach even if just to get the ideas moving and take you away from staring at the blank page! You might discover that some types of talk benefit from an alternate starting point. There really are no rules here, other than that you do end up with a talk before you need to walk out on that stage.