You get in what you put out of the experience...
IMHO, college is easy- as long as you have the right attitude. Ask yourself these questions- Did I do well in high school? What study habits did I develop that will be useful to me? What's my learning style? What's important to my college experience (grades, clubs, organizations, work, partying, etc.)?
Taking the next step in your education is a BIG choice and the actions you take while there will have big impacts to your future success. You're probably only going to be nervous or anxious for the first quarter or so (maybe). There are a lot of factors that determine this- preparation prevents perspiration. Don't succumb to the party life and not study and expect to do well. Strive to achieve that "A." That way, if you do do well but are still struggling, you're not struggling to pass.
If you weren't already enrolled to a university, I'd say to try your hand at a local community college first... It'll break you in easier and has that "high school" feel to it. That being said, if you end up struggling the first couple of quarters- consider that option.
Do your core requirements first!!! I was excellent at math in high school and instead of going to college right away- I decided to serve my country, and forgot a lot of things and ended up taking sub-college level algebra. If there's a way to check the success ratings of your instructors, take that into consideration as well. Some professors will not have a teaching style that are tailored to your learning style. Don't hesitate to ask a lot of questions.
Earlier I mentioned not succumbing to the party life... Have a good time, but make school your priority. Don't let the dorm be your prison. You'll need to break away every now and then to recharge. Surround yourself with peers that strive for similar goals as you. Be confident in your abilities. It helps to be competitive. Have a positive attitude ALL the time and stress less.
You're going to learn a lot about yourself there. While you're young, let school be your focus. Keep in mind, you will be competing for that "dream job" against your peers when you graduate. Ask yourself, what am I doing that will make me want to be hired over them?
What are your degree goals? If you decide to do an associates, bachelors, masters, and/or doctorate... keep in mind there are different honor societies affiliated with all those levels. Phi Theta Kappa for example is an international honor society for those seeking to complete an associates, and it's easy to get into (3.5 GPA minimum with at least 12 completed quarter hours). That doesn't mean it stops there, they will write your letter for you to be accepted into a bachelors program and so on.
There's a lot that goes into college. More than I am mentioning here. Keep your head up! Life is about learning... Have fun there. Anticipate lots of ramen noodles, lol. It all really comes down to attitude. Stay focused and positive and you should do well. Ask questions, seek help from the staff and your peers. You'll make friends there that will last the rest of your life. Explore. blah blah blah... it's easy sauce, if you make it that way.