You can follow below tips to crack JEE Main in 1 month-

1- Make a proper and almost fixed routine for the last one month.
2- Thoroughly practice from NCERT text book and solve the exercise rigorously.
3- Try to solve as many as MCQs for your practice.
4- You should refer previous year papers to understand the exam pattern and level of questions and try to give complete mock test series to know where you stand among other students.

Other reference books for your preparation-

PHYSICS

NCERT textbook and exemplar

Previous years JEE objective type question (single option)

MATHEMATICS

NCERT text book and exemplar

Co-ordinate geometry and trigonometry- S L Lorney

Calculus  I.A, Maron

Algebra- Hall & Knight + Bernard- child

Previous year IIT-JEE question bank

CHEMISTRY

NCERT text book and exemplar

Physical chemistry- P. Bahadur, N Awasthi, Atkins & RC Mukherjee

Organic chemistry- M.S. Chuahn, Jerry March I L Finar

Inorganic chemistry- JD Lee

Previous year JEE question bank.

Important topics for your preparation-

Physics : You should have a fair understanding of Kinematics and Dynamics, and it is essential to be able to build a strong problem solving ability. Also, the Theory of Fields (Electromagnetism) is very important. But do not ignore Heat & thermodynamics, optics and modern Physics. They are easy and scoring also.

Chemistry : Physical Chemistry can fetch you good scores and hence, all the units under it must be done carefully. Students tend to neglect Inorganic Chemistry, but just a proper understanding of it can prove to be beneficial. General Organic Chemistry must be understood and memorized to score well in Organic Chemistry.

Mathematics : Calculus forms a base for almost every part of Mathematics. Other important and scoring topics are Determinants, Sequences, Permutation and Combination. The student must be able to relate the complex numbers with Coordinate Geometry and Vectors. Three Dimensional Geometryshould be practiced to get that additional or compensating score.