It depends, but here are the steps:
1) Learn the opening well: Learn every variation, including side-lines, and practice a lot
2) Know what are the key squares for each side and the pawn structure
3) Once you see a non-book move, see whether it concedes any squares, or weakens a piece.
4) Look at every move possible, including waiting moves to see what your opponent has in mind
I'm sure you are familiar with the "beginning game"..."middle game" and "end game". Should your opponet start out chaotic, than chances are very good they will lose control. Pieces have to work together.
Don't focus on punishing your opponents positional inaccuries right away. Rather, develop your forces naturally and let them suffer the consequences of their clumsy play in the middlegame.
In my opinion,chess is totaly calculation based game,any kind of mistake such as opening mistake or positional mistake leads to serious chance of loosing the game.But i am also realizing that playing as black is quite difficult rather than white,i am trying to build some new algorithm(moves) of my own that will help to play as black.
How does one play against inaccurate opening moves of the opponent...such moves which are not material dropping blunders but ones which are not book moves?
how is one supposed to analyze wrong play of the opponent as the mistakes are very subtle and the opening stage is extremely complex with endless possibilities calculating which is sure to finish one's time?
even if my opponent delays development by pushing pawns i find that ultimately he gains space,chokes my pieces and then comfortably gets his pieces out.how to improve this phase of the play?