It's on a Sunday this year in Denver (THIS Sunday, I think), so I'm not going. First time in...five years? I always make snacks for the Colorado bands to take with them, since they're usually stuck on tiny food allowances and no time to go find anything. And it means I can't wear my Master Splinter shirt this year...
Tips? Yes.
Water. LOTS of it. I think they'll let you bring a large bottle. (Check the website for details.) Drink lots and lots. Refill it at the water stations. I watched one youngish woman just totally faint from dehydration while I was walking by her.
Sunscreen. LOTS of it. Apply often.
Bring a good chunk of money for merch, but keep it close to your person - don't put it somewhere where it's easily snagged.
Get there early. Before they open, ideally. As you walk in, immediately make note of when the bands you MUST see are playing, and where. Bring a small notebook so you can jot down times and plan out your day. It's almost inevitable that two bands you really want to see will be playing at exactly the same time on two different stages. It sucks, but it happens. Make a choice.
Don't schedule seeing bands from start to finish. Do schedule time to wander around the merch tents to meet the bands. The smaller the band, the better your chance of actually getting to chat with them at length. Katy Perry? Probably not. Forever the Sickest Kids? Decent. 3OH3? Definitely.

If some band in their booth looks interesting, go say hi. It's a good chance to get to know some cool bands before they make it huge.
Watch Animo's set, and sing along to "Fuck Yeah!" You already know the words.

And tell them "hi" from me.
Lex