Dear teena, 

I think join the coaching is not necessary for selection of Aiims exam. 

Please follow these points - 

According to me, however strong your concepts are, the biggest practical problem of not taking coaching is getting your doubts cleared. For that, you must make efforts to find some platform for the same using the boon that is internet.

The next challenge is studying according to a schedule everyday, because you are the master of your time table. Just remember one thing. In medical school, you'll have to study more than the 10+2 syllabus in the first year itself. So, studying everyday will only help you in the long run, without screwing up your beauty sleep.

Coaching is not necessary to succeed. If anything, it stifles your natural curiosity by instilling the belief that you need to study not to learn but to qualify in some exam.

If you're motivated enough, you will definitely succeed. Because all you need to get into AIIMS is you and your hard work.

Best wishes 

Thanks for asking