To clear NEET and AIIMS exam it is very important that your concepts should be clear. You can start your preparation with the help of NCERT books as syllabus is based on them. Exercises which are given at the end of each topic is very important.

After, completing your NCERT you can refer HC Verma book. 

It is very important to refer previous year papers to know the type and level of the exam.

Focus on the topics which carries more weightage in the exam.

You can also solve as many as MCQs for your practice.

All the Best!!