Hii Venkatesan!
The only way to prepare well is to study well. PRACTICE. The level of ICAR AIEEA is slightly easy then the NEET UG entrance examination. So, if you go through the NCERT textbooks of class 11th and 12th thoroughly, you will be good. Solve the previous year question papers and questions banks. Practice numericals. Make small notes and revise everyday. You said you are not good in physics, so pay more attention to the subject. The more you practice, the more well you will perform in the exam. So, set a timetable and follow it strictly. Take care of your health too.
Hope this helps.
Good luck!