Hi Vaibhav,

As much as the final result depends on your hard work and strong preparation, I understand that finding good preparatory books can be a daunting task. Therefore, for you reference, I am listing down a few books that have been highly reviewed and recommended to Law aspirants at DU and I hope this helps you too - 

1. Plutus Academy LLB - A complete solution (Publisher: Assembled Notes) - this book has all the important topic covered in an easy language for the students' convenience.

2. S.S. Guide Book for LLB (Publisher; Singhal Law Publications) - addressing specifically the DU LLB exam, this guide has solved question papers for all the constituent subjects.

3. Universal's Delhi Law Faculty LLB Entrance Solved Test (Publisher: Universal) - has solved past year papers for you reference and better practice. 

Apart from these DU LLB focused books you can also refer to these other two guides that are addrressed to Aligarh University and BHU University respectively - 

1. Popular Master Guide LLB Entrance (Publisher: R.Gupta) - For Aligarh University's entrance exam, this book covers all the important topics, collected and combined, from the best online portals.

2. BHU LLB Entrance Exam (Publisher: Arihant) - has solved past years' question papers for your best practice. 

I personally suggest that you you limit yourself to only 2 or 3 books while preparing otherwise the preparation can seem very difficult and also confusing when referring to various materials simultaneously, however, in that case too try to diversify your studies by referring to not just DU LLB specific but other college books like the 2 suggested above to have a firmer grip on subjects like Legal Aptitude for you to have a 360 degree idea of all the possible questions that you can expect in the final exam. 

I hope this helps you and all the very best! Please reach out to me for any queries or doubts or information.