Hello

NCERT textbooks are the best for preparation of WBJEE exam and to understand the basic concepts. You can also refer to some other important books for in-depth preparation such as-

Concept of Physics by H.C. Verma and Understanding Physics series by D.C. Pandey for Physics

Chemistry- Physical Chemistry by O.P Tandon and Concepts of Organic Chemistry by O.P Tandon. 

Mathematics- R.S Aggarwal and R.D. Sharma

Go through the link below to check the preparation tips and important topics-

 https://engineering.careers360.com/articles/wbjee-2019

Good Luck!