Having now successfully navigated my way through almost two months of college and sunk into the rhythm of daily life, I feel qualified to make a few statements about that transition stage that can be fun and awkward and more than a bit strange.
1. Orientation: Make the most of it! Go to the events offered, even the non-required ones. In fact, barring scheduling conflicts, and maybe a little bit of sleep, do as much as you can during this first week. You'll meet your hall mates, the people you'll be sharing a bathroom, lounge, kitchen, and general living space with for the rest of the year. You'll start to tentatively know your way around campus, which can be helpful. You'll get a feel for academics and pick your classes for the semester; you might even get ambitious and plan out the next four years with your advisor. You'll maybe pick a club or two to participate in, or audition for a performance group. Whatever you do, you're staging the rest of the year, and orientation is a week you can't get back, so make the most of it.
2. Go to as many general interest meetings as possible. In the first couple of weeks, they're happening all the time. Go to them even if you don't know if you're interested or not; you may discover a new passion. If there are scheduling conflicts, you can usually contact the people in charge; you'll either arrange another meeting, or you'll just be able to attend one of their regularly scheduled meetings. And even if you only stick with one or two of them, you'll have gotten a feel for what else is out there.
3. Explore the campus. Take some time to go through the tunnels, it'll come in handy in inclement weather (even though we haven't had snow yet, we've had plenty of rain, and I was grateful for the tunnels then). Learn where your classes are, where all the best places to eat are, where to get your mail, where your professors' offices are. You'll be here for the next four years, so get to know your way around. And take some time to explore the library. It took me a while to get past the lobby, but once you do, you'll find plenty of cool places, and without a doubt, you'll stumble across some interesting reading material.
4. Meet as many new people as possible. They're everywhere; in your hall, in your classes, in your extracurricular activities, in the line at the post office. You never know who you'll meet, and who you'll hit it off with. There's a large pool of people to pick from, so don't limit your options. Meet people who are different from you, but also, if possible, find people from where you're from. It's always fun to be able to share regional inside jokes.
5. Get into a routine — but not too much. Get the hang of your classes and your schedule, factoring in things like work and extracurriculars too. Figure out how much time you need to spend studying for your classes, and then make that work for you. But don't get stuck in a rut; just because you said you'd spend 8 hours studying for that biology test doesn't mean you can't take a break and go get some ice cream.