Hey, congrats! Sorry for the delay, I had somehow missed that message.
There's no strict Dos and Don'ts man.. And it depends a lot on the campus as well. Ahd had its rituals, Indore will have something different.
Imp thing is to figure out early as to what you want to do after the 2 years. If you're looking for a top i-bank job or consult job, work towards that from Day 1. If you're looking for more of a work-life balance kinda job, try to achieve that in the campus itself
I cannot stress how important it is to not lose yourself/your aims/what YOU want to do, when faced with the crazy peer pressure and rat race. Don't fall in that trap.
One thing will probably be true - More than the acads, the placements etc, the most important thing you'll gain from an IIM will be your peers and the amazing network that you'll build.
Let me know if you've any specific questions..