Could someone suggest me how to build strong base for iit jee maths?Thanks in advance.

Every practical example is concerned of somewhat mathematical approach.
1. NCERT approach
2. Topic specialized books
a. CALCULUS-- A.M.Aggarawal
b. Trigonometry and vector analysis- A.M.Aggarawal
c. Algebrs and Coordinate Geometry – S.K.Goyal
d. 30 Years old IIT-JEE previous question-solutions paper

‘‘PRACTICE MAKES A MAN PERFECT’‘
All the best’‘‘‘‘‘