One of the key elements of chess strategy is figuring out where the pieces go to achieve maximum strength. Obviously it depend on what else is going on the board, and in rare cases you achieve what is considered "good" position and it does not actually help as much as hoped. That said in general landing your pieces on the right squares makes a huge difference in how effective your pieces are as opposed to your opponents. It's also the case when the tactic break out, if you have well positioned pieces and your opponents do not, it often "happens" that the tactics work out in your favor. So that said, where do the pieces go:
Knights: The knight is a short range piece, it generally does well when it is pushed in the enemies face, and poorly when not. You don't want to spend a bunch of tempo moving a knight around just to trade it off, and you also don't want to move it to an awesome square, only to get chased away by a pawn. The best knights cannot be traded off, and are sitting on a central square that cannot be attacked by a pawn. Assuming we are white, the best squares are e5, d5, e6, d6. The worst knights are on the edge of the board or pushed into a corner where they just don't attack many squares (if a knight is literally in the corner, it only attacks 2 squares, as opposed to 8 squares if it is in the middle of the board. It’s far less likely to be doing anything useful attacking so few squares). The famous "A knight on the rim is dim" is pretty true. This will be a recurring theme, if a piece attacks a boatload of squares and cannot be threatened by a lower value piece, that's awesome, if it does not attack many squares or it can be chased away than it's not very valuable.
This is a good knight: http://i.ytimg.com/vi/cNdGTi_3rLY/hqdefault.jpg
Bishops: Unlike knights, bishops have great range. They don’t need to be in the middle of the action to be useful, they just need a nice long open diagonal. It’s nice if they are pointed at a juicy target like a castled king, but they can be strong on any long diagonal. The downside is of course that they only ever play on one color, and if they get trapped behind a chain of your pawns they become a “bad bishop”. Sometimes a bad bishop is only technical bad, and it’s waiting for the pawn structure to change to come exploding out, and sometimes having a bad bishop is like being a piece down. Certain openings hinge a great deal around the bad bishop (e.g. the French), can black free his piece? Or will the inferior bishop haunt him the whole game? In general you want to try pretty hard to avoid trading your good bishop for your opponent’s bad bishop.
Rooks: Rooks go on open files, and in general they are on open files with the intent to move them into the opponent’s position, either the 7th or the 8th rank (assuming we are playing white). Weirdly the 7th is often stronger than the 8th, although in some cases the opponent is vulnerable to a back rank mate, or has loose pieces on the back rank for whatever reason. On the 7th rank they run around snapping up pawns, and often can threaten mate. The only thing better than one rook on the 7th is two rooks on the 7th, sometimes called “pigs on the 7th”. When I was first learning chess, for whatever reason I believed the advice about bishops and knights, but I thought the rook advice was too weirdly specific. There are games where getting two rooks on the 7th does not win outright, but it’s a tremendous advantage.
Rooks controlling the open file: http://www.chess-game-strategies.com/image-files/d_4_control-of-useful-open-file-4.gif
White has a weak back rank: http://www.chess-strategies-tactics.com/wp-content/uploads/2011/05/weak-back-rank.png
Pigs on the 7th: http://www.kidchess.com/glossary/images/pigsonseventh.gif
