Hello Arya.

For preparing for AIIMS MDS entrance, first of all you should be familiar woth the pattern of question paper and repeated questions asked. Also you have to make your study more objective oriented. You can join satellite classes for DAMS or any other good coaching in India and opt for their Test Series. You can also use MARROW app. 

Along with it, buy some review books and try solving the MCQs given it.

All the best