It's pattern recognition through repetition. You start to pick up on clues and cues. For example, one I often missed but see better just recently is this: If the opponent queen is open to an attack by your knight, and the two of them are vaguely close to the opponent king, look to see if you can give a sacrifice check with some other piece to force the king to move a square to capture. Chances are it will set up a fork of their queen and king by your knight on the next move. 
How to know the theme in a chess puzzle?
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Mar 27, 2022
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#2
I could not find it whenever I see a puzzle.
and usually wrongly complete the puzzles, even the ranged is set to 600~1200.