I find that instead of doing the smart thing, and researching deeply before diving into a project, I tend to research as I paint. Each fueling the other in a feedback loop. If I read about something else it often causes a loss of focus and may even derail a project entirely.
I've always been fascinated by the Prussians and the War of Liberation. Maybe it's my German heritage? Maybe it's just Prussians are cool and something different from British, which one sees a lot of. I mean, the Peninsula and the Waterloo campaign are awfully well covered by just about everyone else. So when Osprey had their sale this winter I got the two thematically appropriate campaign books for some background and perhaps scenario inspiration. They did fill in some gaps in my knowledge, even if the lack of maps, or the text referencing locations that actually weren't on the maps, was a bit frustrating.
Speaking of Peter Young and The War Game, I'll have to peruse it again just for a dose of nostalgia.
Even just to look at the pictures of the old school armies. These pictures really inspired me as a youngster as I built my armies from Airfix figures.