Neet and other competitive exams like olympiads

The preparation strategy can vary exam to exam. You will have to be specific with the exam.
Like in case of NEET:
There should be an effective study plan. Make a goal and focus the strategy to achieve that goal and you will get your path. Now that you have a hold on some topics and sections, do not skip the sections you are weak at. Focus on that too. Some of the important topics in NEET are:
Morphology of Flowering Plants
Ecosystem
Human Health and Disease
Environmental Issues
Digestion and Absorption
Ray Optics
Semiconductors and Communication System
Rotational Motion
Waves and Sound
Atomic Structure
Classification of Elements and Periodicity in Properties
Chemical Thermodynamics
d and f Block Elements
p Block Elements

Prepare these topics score good. Practice tests and mocks accordingly.