Marc P. answered 08/04/19
Ivy League Grad to Help with Standardized Tests and Academic Work
There really is no "right" answer to this question; successful professional writers take all sorts of approaches to this issue. Much, much more important than starting in the right place is simply getting words down on paper. After all, your first draft is not supposed to be high-quality writing; that is what the editing and revising process is for. (See Anne Lamott's "Shitty First Drafts" for a good discussion of this.) Just write!