I never have any less than about three or four docs of plot, character motivations, Notes to Self, and, oh, yes, the ms doc itself, open at any given time on my trusty iMac. I'd need an IMAX-sized screen to accommodate all the docs I could be using!
(Notice, I even have random notes stuck in the clay mug off to the left, sheesh!)
Then I need a print-out of the ms, as in actual paper, to scribble on. (# 2 1/2 pencil: my weapon of choice.) This also helps me to actually see all the typos. I know they're in there, I can hear 'em breathing, but it's much easier for me to see them in print, instead of on a screen.
The final element to a productive work day? All the images I can find for inspiration!
This is my Pinterest page for the book I'm editing now, Beast: A Love Story. Yes, it's a fantasy, a retelling of the Beauty and the Beast tale, but it's rooted in a specific historical period (rural Burgundy, France, ca. 1600). And anything I happen upon while cruising the Interwebs—dress, architecture, various objets, the French countryside, or potential character studies—goes into the file for future reference.
All systems are go for me and my village!