cheers!
i recently browsed thru some expert advice on the web on how to improve one's chess, and eliminate completely those monstrous blunders and oversights. almost everybody answers this by saying that you should improve your chess vision to start with. how? just memorize the board by heart...that you might know every square in it, and point it out, say the square f3 on an empty board without coordinates that is immediately, and be able to transfer a piece, say a rook on b2 to h5 in the shortest route possible. one exercise they recommended was to examine a position from a game (say, a complex middlegame position) and break it down to every piece's control of this or that square, or attack of this or that point... for instance,

in this position we should point out every piece and what they are attacking, defending or controlling. here, for example, white's pieces:
Ra1 defends a4 pawn, controls a2-a3, and b1-f1, Bb3 defends a4 pawn, attacks e6-f7 pawn chain, controls a2-g8 diagonal,etc...
this simple and seemingly naive exercise could actually help us improve our sight of the board and improve our combinative vision too! since i've turned this into a habit (i do this while watching tv, on the way to school, or simply when i had nothing to do) i've seen a lot more, avoided a lot more blunder and oversight, and played better! even in manoeuvring this is beneficial.