Here are some of the things I have found to be helpful:
1. I always book the Mac lab for the first day. No one else ever wants it, and nothing gets a classes attention more quickly or makes them more receptive to your class than technology. Once, we skyped with a class from Texas our first day. Wow! The kids were floored. Instant engagement. More often, however, I have them create avatars using Voki. The kids love introducing themselves in this manner, and it really gives insight into their style. I add all of the Voki's to our class website. You can see last year's here under the avatar tab.
2. Another thing I do the first week is gather a writing sample from my students. I then create a spreadsheet with common areas of difficulty (spelling, comma rules, agreement, etc.) and chart each student with S or W for each area. I immediately get a feel for each student's level and I can target problem areas quickly and efficiently. I can't tell you how much this helps. I always collected writing samples, but until I started charting, it wasn't nearly as valuable as a formative assessment.
3. The last thing I will share is my rule list. I have one, Be Respectful. It is really all you need to run your class. I don't get bogged down in 10,000 rules and regulations like I used to. I expect students to be respectful to me, each other, themselves, and classroom materials. In turn, I always show them respect. There is nothing more important for a classroom than mutual respect.