Enjoyably keeping a large painting project going for several months (if not years) really requires a mental game working in the background. Having a good pile of reading goes a long way towards keeping the enthusiasm for The Project at a high level. Though my collection of references for ECW are minimal at the moment, I'm having to rely on primarily internet resources (re-enactors and wargamers) for uniform and battle information, I did find this book at the local town library and so far its is pretty good as a general history that is rich with detail and gives a great sense of the period and its characters so important in bringing life to a gaming experience. Since I'm "across the pond" the ECW is a more distant period to collect than might be if I was going in the American Civil War direction. So I'm finding the period more exotic but because of that, very compelling! I've also got my eye on the Partizan Press offerings but at the moment every spare cent has to go buying more metal! That can lead to some missteps in the colors of uniforms, flags and such so I have to be prepared to backtrack occasionally as my knowledge of the period improves. Fortunately the ECW was prior to strictly uniformed armies and I can chalk up any mistakes to the scarcity of records from the period...and just enjoy the pageantry that I am able to produce with the references at hand. Having a set of rules already in hand helps with basing decisions so at least that direction is taken! I've also found that the website of the "Sealed Knot Society" has a good list of the units they re-enact with a basic color reference for coat colors of the various regiments. Many of the regiments also have websites with flag information that helps complete things at least to my "game table" satisfaction.
I really love the research end of the hobby so I know this period will provide many satisfying hours of digging in order to find (for example) the flag of "Haselriggs Lobsters" (... anyone knowing this one...please post!).