Talk to everyone - When you first turn up at your accommodation/flat or whatever, it's so easy to just stick with the first people you speak to, or to your flatmates, who are instantly familiar to you. But it's important to chat to as many people as you can in your halls, because you never know who you might get on with. And you can meet some pretty interesting people during those first few weeks! So remember to get out there and just be friendly.
Join a society (or societies) - The old university cliche. Everyone tells you to get out there and join as many societies as possible. But seriously, they say it for a good reason! Most societies offer completely free trial lessons/classes/meetings in the first few weeks of term, to give you a chance to try out different things to see what you like before committing. They are such a good way to meet new people and try things that, to be honest, you don't ever really get the opportunity to sample again, in this much variety (and for free) after university. Really, I wish I had joined more societies, as the few I did go to were such a laugh and really fun. And they don't need to CV-boosting and all that. They just need to be fun and something you enjoy. Hey, my uni even had a Harry Potter society! Not sure which employer would see that as a bonus...
Work hard (but not too hard) - Okay, so this one applies to basically the whole of first year, as opposed to just the first few weeks/months. At most uni's, first year doesn't contribute to your overall degree. So it is DEFINITELY fine to be a bit more chilled out about your studies, and not majorly stress yourself. University learning is a bit of a game-changer from sixth form/college learning so give yourself time to adjust. However, I really do think it's a good idea to work hard and really try your best with essays and exams in first year. Mostly, because it gives you a great foundation to move off from after first year into second and third, and also, because it helps with feedback. Tutors can only give you accurate feedback if you're working at your best at the time, and getting honest, helpful and constructive feedback can be so useful (it was for me) for those trickier second and third year exams and essays. Working at your best and not spending too much time hungover (or out) can give you a confidence boost for the year that actually do count.
Go out - And on a completely different note! Make sure you make time to go out and have fun, and explore your new city/town/country. Honestly, some of my best memories of uni are from first year, either from crazy nights out, cute nights in with my flatmates, or just spending time getting to know my new home and any attractions it has. It can be easy to just stay in the bubble of your university and work and reading, but rarely will there be a time in your life again where you have so much free time, and not a huge amount of responsibility, so go and make the most of it