A couple of years ago I received the good fortune to attend NECC (now called ISTE) as the NECC Newbie. NECC/ISTE Newbie was an experiment in using social media to raise money. Beth Still organized the whole thing and you can read all about it on Beth's blog.
I won't be attending ISTE this year (my schedule is just too full with other engagements), but that won't stop me from sharing my advice with those of you attending for the first time.
1. Make sure you charge your phone, tablet, laptop every night. Power outlets constitute prime real estate and you might not always be able to find an outlet when you need it. That said, bringing a power strip and sharing it is a great way to meet new people.
2. Say hi to the people you think you recognize from Twitter, Classroom 2.0, and other networks. You might feel stalkerish doing it at first, I know that I did, but trust me no one thinks you're a stalker. Along the same lines, say hello to people next to you in the sessions you attend. Part of the ISTE experience is connecting with other educators to share ideas and learn from each other.
3. Take a lap through vendor showroom, but don't spend too long there. Companies spend thousands to be on the showroom floor and are good at showing off their shiniest newest products. Just ask yourself before you sit down for a half-hour sales pitch, "will I benefit from spending my time here?" For a lot of classroom teachers the answer is probably not.
4. Don't underestimate the importance of good shoes. You could end up doing a lot of walking during the day. Go for comfort over style.
5. Attend all of the formal sessions you want and can get into, but if you find yourself in a session that doesn't "do it" for you, it's okay to leave early.
6. If you want to see samples of what teachers and students are really doing in their classrooms, go to the poster sessions. I've found those displays to be the source of some great ideas.
7. If you're a cheapskate like me you can fill yourself on appetizers at vendor-sponsored evening meet-ups. See #3 above to find out where and when they are happening. Also see #1 and #2 to make connections and find out when and where meet-ups are happening.