Pranay, the questions in OG successively get harder and harder, dont worry.

But one thing concerns me, havent you read CR theory before starting the practice?

You should be aware of question types, such as

Inference
Must be True
Most Supported/Strengthen
Assumption
Weaken

and how to approach each question type.

Hi Arora,

Thanks for taking time to respond my query.

I have referred the Manhattan GMAT guide before practicing OG questions.

I am aware of how different critical reasoning question types and have an idea on how to approach them (theoretical).

May be 'Practice makes a man perfect' holds true in this case.

But, what is concerning me is the drop in success rate from 85% to 50%. Is this usual?

Is 85% a good success rate while answering the OG questions? Will my understanding help me fetch a good score in GMAT?

Your suggestions are valuable and please suggest me what to do. I am open to what ever needs to be done to see a good score on GMAT.

Pranay, the drop is certainly quite drastic, were you solving these questions under a time pressure?

You need to figure out where your understanding fell short. For example: if you were solving a weakening C.R.

Was it that you were not able to find out the conclusion which you had to attack?

or

Was it that you forgot that weakening questions require you to attack the conclusion?

However If you never knew that to approach a weakening is to attack the conclusion, then I would be wary to solve more

CR questions until I figure out the theory in completion.

Don't be bothered of the occasional trap question! And yes.. do keep an error log. Review your mistakes as often as possible!