Common techniques for memorizing data for UPSC exams include using mnemonics, visual aids like charts and mind maps, and practicing active recall. Flashcards are particularly effective for quick revision and retention of key facts. Regular self-testing on important topics can solidify memory. The method of spaced repetition, which involves reviewing material at increasing intervals, enhances long-term recall. Lastly, summarizing complex information in one's own words can aid in absorption and comprehension, facilitating better retention during the exam.