hello aspirant,

YES, your class 12th score didn't matter much, if you are looking to crack JEE mains or advance exam. You can crack JEE mains and JEE advance after taking a drop if you get focused and be disciplined and practice on the right preparation strategy. If you have make your mind for the drop, then I would suggest you to forget about your this year's JEE mains score and focus on your target score for the next year in your mind. KEEP repeating that in your mind (if you are serious). Practice previous year Question papers, revise all concepts regularly, make a proper timetable, practice difficult questions from High-level books like Cengage, Arihant and I.E. Irodov, then give mock tests, take rest and repeat the process.

Below are some of the best Preparation tips that I would like to give to you :

Prepare A Well-laid Plan

Draft a daily schedule.

Prioritize the topics that require more time and relevant to the subject.

Stick to the routine and pay special attention to problems.

Get Hold Of The Syllabus

Manage your time effectively

Understand Basic Concepts

Before delving into JEE preparations, know the JEE syllabus and understand the basic concepts present in the syllabus.

Evaluate your knowledge on basic concepts.

Make notes on required topics.

Choose The Right Study Material

Further, below are some of the best Books for JEE preparation :

JEE Main Books Important for Mathematics

Trigonometry by S. L. Loney

Higher Algebra by Hall & Knight

Maths XI & XII by NCERT

Coordinate Geometry by S. L. Loney

Problems in Calculus of One Variable by I.A. Maron

JEE Main Books for Physics

Problems in General Physics by I.E. Irodov

Fundamentals of Physics by Halliday, Resnick & Walker

Concepts of Physics Vol I and II by H.C. Verma

Books for JEE Main Chemistry

Organic Chemistry by Paula Bruice Yurkanis

Organic Chemistry by Morrison & Boyd

Inorganic Chemistry by J.D. Lee

Numerical Chemistry by P. Bahadur

Further, For more information and complete details about the JEE mains tips and strategies and about the subject wise weightage in JEE mains, you can follow the belwo link :

https://engineering.careers360.com/articles/jee-main-preparation-tips

I hope that this will help.