There are many books for JEE main and AIIMs .The best way is that you follow traditional books which are guidance provide by your senior and peers.Firstly follow the NCERT books of both years for making concepts then for physics follow H.C.verma ,for  chemistry follow O.P Tandon and for maths follow M.L. KHANNA and for biology follow K.N Bhatia.

After this you have to solve previous year question bank to get the experience of question that are asked in the exams.

To know more about Books for JEE main follow this link:https://engineering.careers360.com/articles/best-books-for-jee-main-2019

To know more about Books for AIIMs follow this lnik:https://medicine.careers360.com/articles/best-books-for-aiims-mbbs

Hope this helps you.

ALL THE BEST.