Hello Nikhil

Its all about your concepts and how much deeply you go through all topics .

As of the experience it is not enough because all you need to do is practice all concepts with different questions and  it's the only way you can improve your results. As you should start with NCERT and RD. Sharma but you should go to some other books after practicing these books .

Sone of good books are : Arihant by amit m Aggarwal for calculus and differential, vectors , complex numbers .

ADas Gupta for trigonometry and algebra .

Cengage learning .

After that you can go with black book of mathematics ( only if you are well prepared with your all syllabus ).

You should solve the DPP s and package of any one  good institute like ( Bansal, allen etc.).

All this helps your thinking ability and provide you a good stuff . It increases your efficiency and conceptual knowledge also.

Good luck

Hello.

RD Sharma is one of the best maths book available for class 12th, however RD Sharma is more based on the boards than jee. RD Sharma is wonderful book for practising, but if you are preparing for jee, I would not suggest you to follow RD sharma. However if you are done with jee syllabus and have practised from some book based on jee main and you want to enhance your problem solving skill, then you can certainly refer to RD Sharma.

Hope it helped!