Hi yogasree , if you work smart, you can really score well easily, i will tell you how to prepare 

Physics and chemistry- physics is considered one of the toughest subject for medical aspirants,but very interesting. choose any good book of your convinience, there are plenty of good books as many mentioned already. read the concepts thoroughly,understand them cover to cover, if you have doubts, clear them then and there. solve atleast 300 to 500 questions per chapter, check ,analyse and rectify your mistakes. solve again. the more you solve the merrier.initially you wont be getting many correct answers, but as you keep on doing am sure you will see your score rising. solve previous question papers too

Biology-aiims doesnt cover most part from ncert like how neet does, in neet around 300 marks are from ncert text book itself, so u need to thorough ncert first and then read any good book of your choice and solve as many questions as you can

General knowledge and current affairs- read newspapers regularly, keep yourself updated always, use year books, they ll help you alot.good luck