First off always treat Officers of the law and every other person you encounter with respect.
The cops are doing their job. The assholes are just assholes and need no excuse.

Do not deal at an event. There are always narc's in the crowd, you will get busted...
Do not bring any paraphernalia, pipes bongs and such will get you busted.
Do not bring more drugs than you reasonably expect to consume.
Do not bring any weapons of any sort.
Do not get totally fucked up a person out of his mind does the cause no good.
If you plan on smoking or partaking plan on being arrested,

This means having or knowing where to get bail money
And letting someone know where you are going and
What you plan to do in case you don't make it back

Lastly, Have a good time
but pay attention to the speakers and their messages,
so you can pass it on to those who did not make it to the event