One of my favorite tips is:
Don't shoot your wad early in the week.
(That's actually Tip 20. It's okay to take breaks. but he ends the tip with these words, which are now vividly etched in my memory ;-) Here is the full tip:
20. It's okay to take breaks. Your first time, you're going to be tempted to go to every session you possibly can. Somewhere around Wednesday or Thursday, though, that effort combined with lack of sleep, is going to take its toll on you. If you're too tired or overwhelmed to process information, it's okay to hole up on a couch or at a table instead of going to a session, or even to go back to your hotel (you did get a close one, right?). In fact, it's a darn good idea to map out a few "sacrificial" time slots that won't feel bad about missing just in case you need a break. You don't want to burn out and then miss something you are really interested in. And some of the best, more advanced sessions fall at the end of the week, so don't shoot your wad early in the week.
This is actually a tip I should have heeded better last year. I did not pace myself and I ended up getting the WWDC Plague near the end of the week.