Right, I've an idea for a non-fiction project that I think would be really interesting, I'm just having a bit of a mild freak-out about the research. Basically, it's about World War II from the perspective of the wives/mistresses of the world leaders (FDR, Churchill, Stalin, Mussolini, Hitler, and Hirohito) Two problems. (1) HOLY CRAP WHERE DO I EVEN START!?!?! (2) Stalin had no wife/mistress during World War II as she died before the conflict began. So...yah.
I'd start with Eva Hitler and Eleanor Roosevelt, as they were prolific in their own right. Not that Clementine Churchill and Rachele Mussolini weren't, but fewer people are aware of them than of their husbands. I'd start with the biographical data, figure out where they might have appeared together (at least at the same events), and look at the gender roles and expectations of the era. That'd probably give you a better idea of what kind of story you're looking at. It sounds like it could be an interesting read.
Maybe start with the 1936 Olympics in Germany, where most of the major players in WW2 (as far as nations) participated. There could be something to that.
Holy balls... And I call myself a history major! That'd be a perfect thing to examine -- how society would've expected them to act versus how they personally thought of the war their husbands were waging. What could they have done? And how much?
There is also the realm of very very very heavily researched historical fiction, though. I recently read something about The Decision, by Bohler, which is the sort of thing that I mean.
I'd second the advice to define a research question, and then I'd add that you're going to have to do a lot of reading. Anything that's even tangentially related. Like, thousands and thousands of pages, if you're serious about it. Most of which will never be directly useful, but as far as I can tell there just isn't any shortcut when it comes to research.
Book suggestion: No Ordinary Time by Doris Kearns Goodwin. (Subtitle is "Franklin and Eleanor Roosevelt: The Home Front in World War ll") I'm not a war buff, but I love the homefront / people stuff, and this one is very good. Good luck!