NAT - I think the important thing when dealing with a trick question is understanding what the question is actually asking. You might identify key words by using a highlighter (as one example).
The best way to eliminate misconceptions is to have a solid understanding of the processes required to answer a question. For example, a simple error such as using an unordered data set for calculating the median is one that could be easily rectified by understanding that before hand. Practice is key. You can rote learn or try to memorise formulas, but without practicing and applying them in questions... it will be very difficult come test/exam/assignment time.
Just remember for your Further exams, you are able to use a CAS calculator (such as a CASIO Classpad or TI-nspire)... I would definitely learn how to use that in depth because these calculators will do the hard work for you.