Some people believe that a shrewd player is the kind of player who somehow manages to think about the whole board all the time. While not being that kind of a player myself (still a lover of silly mistakes), I know it for a fact that thinking deeply about everything all the time doesn’t even exist in a shrewd player’s wish list. Count on it.
Apart from words arsenal or strategy (or whatever), the key is knowing where to look, and how to deal with it. Where?: focus on the area(s) where it matters most. How?: find a way to deal with it—with what we have on the rack. The point is: think only as much as necessary. That is: never make a habit of giving too deep a thought, for it will surely wear us out.
Decision making is indeed an art: there are no exact rules. But before we decide anything of consequence, it would serve us good to know where to begin with in the first place. And a sensible start would be the sector(s) of the board where the ‘intensity of conflict’—factually or potentially, is the highest (here, they are indicated by the yellow arrows).