metallicafan, happy to help here
For SC, OG is the bible I feel. I stopped using the MGMAT SC
books after a few days. all those rules kind of didn't go well with me. I needed practice and not abstract statements like "a clause follows here etcetc". Ofcourse, I found the Aristotle SC to be a good read. It helped me. Very concise book I must say.
For CR - I had the same problem as you! The OG did not help me much and neither did the CR questions have any pattern (as the OG) in the actual exam. But, for SC the patterrn/errors tested were very much in line with OG 11
or OG 12
I religiously read through the Powerscore CR
bible. This book immensely helped me. I went through the books 3-4 times until CR became second nature for me. And ,yes practice also helps a LOT in CR. Get your hands on LSAT material if you have run out of problems. Try to go through the first 3- chapters of the powerscore CR
bible very meticoulously and take notes if you feel like.
Understand the passage well
Identify the conclusion(most passages will have a conclusion)
Read the Question
Mark off typical wrong/incorrect answers and then narrow down your choices to the best answer. Many trap answers atttack the premise of the argument but do not attack the conclusion itself, so eliminate such answers
When you practice CR, try to do it by question type. Fo example, 5 questions on weaken type today. 5 questions on strengthen tommorow etc. This will drill the questions types and related correct or incorrect answer recognition into your brain.
Good Luck. Let me know if I can be of any help. PM me if you wish.