I'll second Understanding Comics and The Design of Everyday Things.
Now, about game design books. I admit I found many of them useful, just to have very clear in my mind what a game is, how it works, of which parts it's made. I have found Rules of Play a very good foundational book on this matter. It's true, it won't teach you how to be a game designer.
But it clears you any doubt about what game design is about. The how part is covered pretty well by Schell's Art of Game Design, which is a book I carry with me most of the times in the form of his deck of lenses.
Though I believe it's right to say that good game design comes from experience in actually making games and from an endless critical play (of every game, not just videogames), to me, books are of great aid to look into different point of views and methodologies.
Unfortunately, most of them tell pretty much the same things, so basically you have to choose wisely, or you'll end up wasting time.
Another great aid in my job is keeping up with articles on game design. Mostly Gamasutra and Game Career Guide. MDA model, the skill model by Daniel Cookman and others are the basis of modern game design and certainly shouldn't be ignored.
Finally, being passionate about games, I read a lot of game studies books. Bogost's Persuasive Games, Juul's The Casual Gaming Revolution and in general the MIT press books are really interesting and they often offer fresh point of views on the matter (for example the demistifying of casual and hardcore cathegories made by Juul is something every game designer should read to better understand her audience). But games are the true research fields. Games are at the core of it, as Ian Schreiber gracefully summarizes here