When I first visited the Uni I ended up choosing, I was told a valuable piece of information by the student guide. Make your mistakes in the first year. Aside from more intense degrees such as teaching, marks from the first year do not count towards the final degree. There are only two options: pass or fail. So yes, that does mean you can blag it in the first year and tighten your studies up in the final two or three.
Lots of people say they go to university for the experience as well as the course. Today, it's so easy to be accepted into Uni that lots of people just go for the experience. To these people, the degree feels like a chore, cutting in to precious "me time" when the deadlines begin to loom. Among some there is an unspoken feeling that study time is wasted time (especially at less prestigious Unis), and you aren't getting the most out of the Uni experience. This is wrong. Think about it, you'll be steeped in debt when you leave, and if you come out with a grade that reflects the neglect you treated your studies with, it will be hard to find a job to pay those debts off any time soon.
Don't feel as though you must jump straight from college to university. If you find yourself browsing subject choices again and again, umming and ahhing about what would be a half decent course to take, there is a simple answer: don't go. I've seen people grow bitter at their course, getting the rage at having to study. Well, isn't that why they came here in the first place? University is always there, will always be there. Taking a few years out then choosing a subject you genuinely enjoy is an infinitely better option than going because it'll postpone having to get a full time job for another three years.
Don't get me wrong; it is an experience besides the course. But the socialising, the living away from home, is only a portion of the entire platter of enriching things that university has to offer.
So, like I was saying, if you can enjoy your first year with a couple of hangovers and a half respectable grade you're doing well.
When you get into the second year, it slowly dawns on you that this work counts. Allow yourself to adjust for the first few weeks, as the workload tends to get heavier. I'd be hypocritical if I said plan far ahead, but have at least some idea of the final deadline and exam dates, and correlate your studies to coincide.
As for the workload itself, tackle it with a specific day of the week. Tell yourself you're not going out, no matter what is happening (so it may be better to choose a less eventful night - Sunday is a universal favourite so long as you keep the TV off), sit in, study and repeat next week. Of course, do your homework for lectures when they are due in, but an evening of general subject study will boost your grade up some serious notches. Your work will reflect your knowledge.
As the deadlines loom closer, up your study time to two or three days a week. It depends on your individual course how much study time you should have. University course packs recommend hideous amounts of study time that I'm sure no student has ever stuck to. So be realistic. Give yourself enough time to read the course texts, it'll be useful later when you have to give references in your essays. All academics love references, so like I said before, spend time finding more. References outside the course texts will give the impression that you give a damn enough to work off your own back.