Advice for music festivals like Bonnaroo...?

I'm going to a music festival soon it's two days long (friday, night,
saturday, night, leave on sunday). There are three stages and
camping...

So, what should I plan on bringing? What should I plan on wearing,
it's in Aug. Glass is allowed at the camp area, just not in the venue
where the shows are going on. It's my first music festival so I'm just
looking for some advice from others who have been, like what did you
wish you knew before you went?

It's Kanrocksas.