Reading habits that enhance retention and recall for UPSC subjects involve making active reading a priority, which includes summarizing and questioning the content read. Setting aside dedicated time for thematic reading can help interlink knowledge across different subjects. Utilizing highlighting and marginal notes can emphasize key points for quick reference. Regular revision, including revisiting notes and engaging in discussions, reinforces memory. Additionally, employing techniques like the Feynman technique by explaining topics in simple terms aids in solidifying understanding and recall.