Psychology of moving a piece I've noticed that many amateur games degrade incredibly once they enter mid-game (meaning move beyond opening theory).

There are some great questions and suggestions about improving mid-games, such as strategies to improve positions etc.

Yet, many players with mediocre ratings (myself included) cannot help but make impulsive moves, blunders, simply because they have not approached the move carefully enough.

So my question is this: Does anyone have suggestions for improving mental discipline when making moves?  I'm thinking of suggestions such as; examine how your move might weaken positional defence; or, have you observed how many pieces are attacking the square your moving too?

There has to be some methodological way of improving one's game by improving one's mental discipline.
Yes good habit building is necessary. You need a chess-checklist in your mind. Prepare your checklist before a game, and then go into the game while using it. As you become a higher-rated player your checklist will evolve.


Look for all the "check" moves you can make in a position at each turn.
Look for all the "threat" moves you can make in a position. (this may include simple tactics)
Look for all the "tempo" moves you can make in a position. (as in, attacking a piece that forces the opponent to move).
Look for all the complicated tactical moves, combinations of moves.


As you evolve the checklist becomes smarter:


Look for all "double threat" moves. 
Look for all "tempo" moves but also "counter-tempo" moves (where the enemy moving the piece is actually helping your enemy's position become better).
Look for all the counter-checks
Look for all undefended pieces
Look for all weak points in enemy structure


These checklists become more elaborate in the mid-game and you play slow-games to build up that habit, until it is subconscious. Then you can play faster games.