Well, the obvious first question is: What subject do you want to write about?
What?
Sex and gender in media
Like fiction, non-fiction "tells a story." You have a beginning, a middle and an end. The traditional suggestion of writing an outline is much more relevant to non-fiction than it is to fiction, as you should not just make it up as you go.
What your non-fiction piece is about will determine some of your structure. For example, if you are writing a history book, most of the book will detail events in chronological order. If it's explaining your theory of cell genetics, you have your thesis first, show the evidence, describe the experiments done to confirm your thesis, and end with a summary of what you discovered.
Seeker of Pie
Well now that that's established, is there anything specific that you wanted to ask for help about?
Earth Needs Gentlemen
The future of warfare in UC.
Ironically these days I write more non-fiction than fiction as part of my "Today in the Naval History of World War 1 and World War 2" threads commitment over on World of Warships.
Nous restons ici.
Essay writing is it's own art, every bit as difficult and rewarding as fiction, but different.
Has anyone ever asked for help for non-fiction in Writer's Block before?
I'm now considering some bit of non-fiction.