So, I've been taking LSAT courses and studying everyday for hours on end in preparation for my October exam. I took my 2nd diagnostic exam and did worse than my 1st exam. I figured because more than half of the LR questions were type 2 and 3 (strengthen/weaken) and I'm still having difficulty grasping the concept. I understand what it's asking, but am finding it so hard to get to the correct answer choice. Can someone please help me? In dire need, thank you!

[Admin note: edited thread title for clarity of question type. Originally "type 2 and 3 questions".]