Imagine you’re playing a game of chess. You’ve developed you pieces well, and have a positional advantage. It seems as if victory is certain. Focusing on your plan, you quickly play what seems to be a great move, trying to further your advantage - only to realize that you left your queen hanging.
Blunders (very bad moves) like this can turn a a winning or drawn position into a losing one in a single move. To prevent this from actually happening to you, always ask yourself 4 questions before making a move:
1. Is the opponent’s king in danger?
The first question you should always ask yourself is whether your can checkmate or force checkmate in a few moves. If the answer to this question is yes, you have already won (if you have calculated correctly) and can skip the rest of the questions. Congratulations!
2. Is my king in danger?
If you weren’t able to find a way to win immediately, then you should ask if there is/will be a checkmate threat on your OWN king that you need to deal with. Even if you have a plan to force checkmate in 2 moves, going forward with it would be useless if it allows your opponent to checkmate you next move.
3. Are any of my pieces/pawns under attack and hanging/underdefended?
If neither king is at risk, your focus should be on your pieces. If any of them are undefended, defended less times they are attacked, or being attacked by a piece with less value, then you need to deal with the threat immediately. This can be done by moving the piece or by moving another piece to defend it.
4. Am I forgetting to (re)capture?
Unless there is a very specific reason to not (re)capture in an exchange (such as a sacrifice/in-between move/decoy), you should always ensure that you are winning/winning back material, unless your position prevents you from doing so.
Additionally, make sure to recapture in the best order. In the case below, recapturing with the queen first would be a huge mistake!
All Images were created on chess.com