prephrasing flaw questions

hi, I was wondering if anyone had any tips for prephrasing flaw questions (especially harder ones)? I have a hard time getting the right prephrase down and then I look to the answer choices and it skews my thought process even more. I have a very good understanding of general flaws (as written in Loophole and Powerscore) but prephrasing is always difficult on more niche, case-to-case questions (especially towards the 15-25 range).