Hyy gauri, 

The best way to prepare . . .

for the CLAT LLM, DU LLM, AILET PG, AIBE and other similar MCQ based exams is to keep practicing as many MCQs & mock tests as possible.

Typically the syllabus for these exams includes most of the subjects from the LLB course.

There are some nuances, like extra emphasis on Jurisprudence & Constitutional law in some exams, some topics are dropped out completely in AIBE etc.

So, solving previous papers helps in getting familiar with the questions, pattern and syllabus.

Also, there are important questions which are often repeated from previous years and also adapted or variations from other exams. I can confidently say that if you are thorough with previous papers + selected important questions, you can easily score 85%+ in these exams.

With extensive practice, you can easily identify the answers to most questions; saving time to think and answer the unfamiliar questions.

For example; if you get a question “which article of the constitution talks about the Right to Equality?”. Studying theory will help you understand the background, the implication and nuances of the article - but for MCQ based questions, you just need to know the answer; even if you don’t know the theory.

This can be achieved only with extensive and repeated practice of important MCQs.

I hope this helps