All the way through school - up to the first half of graduate school [masters degree in electrical engineering] i had NO idea what i was doing!! Me dad never finished 8th grade, and me mum finished high school & then took a short course to become a secretary. That was the sum total of 'academic experience' in my family!! Halfway through grad school, i realised that i wasn't going to make it if i didn't 'clean up my act'. The problem was, that i would study (revise) for days and days, and learn lots of stuff - but most of it never appeared on an exam. Most of my revising, therefore was a waste of time - i might as well have been playing video games.
I figured out, what i had to do, was to study almost exclusively what i WAS going to be asked on the exams. In order to 'suss out' what the instructor thought was important, i kept track of the amount of lecture time that they spent on each 'topic', and how much work they did - when they were covering it. As an example - if they took 20 minutes to cover 'topic a', in which they talked about it for 5 minutes, and then spent the next 15 minutes drawing diagrams on the board, i would assign a 'weight' of 1 to 3 for 'just talking', and 4 to 6 for drawing on the board. For a medium complexity talk i would multiply 2 by the 5 minutes - giving a total of 10, and add that to the drawing part - which was 15 times 5 (for a medium complexity drawing). This resulted in a 'weighted score' of 75 for the drawing part. Adding the two together gives 85 for the coverage on the topic on that date. I would then add together the 'weighted score' for every time that topic was mentioned - to get the total score for that topic. I then 'ranked' all the topics in decending total score. Figuring that there was time to work 5 or 6 problems on an average exam in electrical engineering, i would take the top 8 or 9 topics, and learn everything i could about them - working problems i had constructed in the same way as class or assigned problems on those topics.
The first time i did this - i hit the guy 100% - i had every exam problem (on the real test), and NO extras. it was a 'slam dunk' - i did an hour exam in 12 minutes. I then took 5 minutes to check my work. A total of 17 minutes to do a 1 hour exam!! My performance on exams increased dramatically after that!! The two other guys in my study group couldn't believe it. When i first showed them my 'sample exam' (1 week before the real test), they didn't like any of the problems. When we walked out of the real exam, they asked: "HOW did you do that???"
Best of luck!!