It is normal to feel a bit lost and lonely.
Most college freshmen experience homesickness. Anticipate it. Even if you have friends or acquaintances from your high school going to the same university, it is unlikely that they will have a ton of time to hang out with you since they are figuring out the ropes just like you. You and they are learning to understand where to shop for essentials, how dorms work, where to get food, how to manage your finances, what to do if and when you fall sick, how to navigate college classes, and how to find your way around campus.
You are NOT the only friendless person on campus.
Everyone is trying to fit in. Unless you are naturally social, getting to know people may not come easily to you. Many kids your age are still developing their social skills. Like you build physical muscles by working out, social skills are built through practice. Just like you can injure yourself in workouts, you may get emotionally bruised. Do not beat yourself up for social gaffes. Those are par for the course. Chalk those up to experience. All experiences, good and bad, build your personality and character.
Discuss your feelings and fears with mature people who care for your well-being. All universities have mental health services. You do not have to be severely depressed to seek help. You may have academic or social difficulties. Those counselors have experience with many students like you. They may be able to suggest strategies that help you cope with the new life pressures.
While on the topic of homesickness, it is hugely relevant that you are at the stage of life where you want to have a boy/girlfriend. Try to compartmentalize your romantic life (or lack thereof) from your academic life. No matter the state of your love life - whether you have a romantic partner or not, whether things are going well in your relationship or not, whether you get dumped or not, you still have to make the most of your college education. Again, for whatever reason, if you cannot handle your emotions affecting your grades - at the risk of sounding like a broken record - please seek professional counseling. There is no shame in doing that.
Learn how to manage your time.
One of the biggest differences between high school and college is the amount of free time you'll have. Instead of spending a big chunk of time in the classroom as you did at high school, you might spend a fraction of that time in lecture halls. It might seem like you have a ton of free time, but this is where many freshmen falter.
Learn to structure your out-of-class hours for study and leisure. There will be distractions. By structuring your time proactively, you will more likely to use your time well.
Talking of distractions, if you know that you have, say, a Youtube addiction, create a strategy ahead of time to deal with that in college. You are on your own now - no parents around to pull you up.
Socialize wisely
The good news is that you are now done applying to colleges. When it comes to job/internship interviews or grad school applications, an impressive array of extra-curriculars that you did in the past just to impress college admission committees is not necessary anymore. From this point on, focus on getting involved in extra-curricular clubs that not only add to your major skill set but also bring you joy. To lay the foundation for a happy and successful work life, aim to a) build a very strong academic foundation in your field, b) gain knowledge of related fields, and c) stay up-to-date with developments in your area of choice. This will involve both studying and networking. Find clubs on campus that have the potential to contribute to your goals. Figure out how much time you have and invest the optimal amount of time into club activity.
Keep up your GPA
You might be taking many introductory-level classes, but that doesn't mean they're not important. Doing well in these classes will help your GPA. It’s harder to get A’s in higher-level classes.
Grades may be an imperfect reflection of what you learn in your classes. Yet, they do provide you with feedback.
Go to class
This may seem like an obvious thing to do. However, the sudden realization that attendance is not compulsory may lead to truancy. Attending class helps reinforce the information in the textbook and gives you a chance to get to know your classmates and professors.
You'll be able to ask questions in class and get noticed by professors. This is important when it comes time to ask professors for help landing an internship or even a job after graduation. Some professors give credit for being there (class participation points). These are the easiest points you'll ever receive in college.
Get to know your professors.
Meet them within the first couple of weeks of classes. Ask them, “What should I do to succeed in your course?” Talk to them after every assignment is graded if you are unclear about how you lost points.
Professors have office hours for a reason. You may be surprised that very few kids take advantage of this. Usually, the reason is the fear of making a bad impression on a professor. Remember - professors are also human. They were young freshmen once upon a time. They have made their fair share of mistakes in life. Some of them may be parents and very familiar with challenges faced by kids your age. Approach them for advice. I can guarantee you that a majority of them want to help you.
Maintain a Calendar
Keep track of due dates of assignments and dates of quizzes and exams. Start assignments as soon as they are handed out. Do NOT wait until the last minute to get clarifications. No professor likes getting emails at the last minute with questions about the assignments. It is also not a good look to bargain for points on assignments returned after the due day.
Last but not the least
Go to college with a positive mindset. These are challenging but precious years. You will. learn a lot about academic subjects and about life in general. Quoting Forest Gump, life is like a box of chocolates. There is uncertainty about what each day/quarter/semester/year will bring. Try to savor all moments. Enjoy the good ones, and learn from the bad ones. You will only come out as a stronger and wiser person in the end.