hey there

getting 300 in jee mains paper 2 is honestly tough as you will be in the toppers and thus it requires serious dedication. some tips are

1. First of all it has three sections aptitude, maths, drawing. out of these if you want to get 300 then focus on all in order to get such good marks you can not skip any chapter as who knows which chapter question will be easy.

2. Maths is important you need to focus on maths just solve RD sharma, NCERT and other materials if available.

3. mocks are important practice mocks as much as you can it will improve your accuracy.

check the link

https://engineering.careers360.com/articles/jee-main-2020-preparation-tips-experts

good luck