Become a bafflingly and slightly worrisome semi-psychotic fiend about your marks and pretend not to be one when you go outside.
I feel bad for giving this shitty answer even though I gave it because it is literally the answer to your question.
What do I mean about being a semi-psychotic fiend?
Really, by this, I'm just talking about a hyper sense of discipline that pertains to your marks less than it does your studies (as your studies will only function as an extension of your pedanticness over your marks -- if you take the 'fiend' route).
To give you an example, the first year Philosophy unit "Life, Death, and Morality" has 10 "bonus" quizzes that are each worth .5% each. So if you complete all 10 successfully, you can get 105% for the unit. Now, in my first year, if push came to shove I would likely have stayed up all night if it meant getting that .5%. (I'm serious).
This is a pretty extreme example, though, but the principle I'm trying to invoke is the idea that
you need to care about the little things because they add up. The .5% probably doesn't make much difference, but what about an assignment worth 5%? 10%? 15%? I treat them all like a major essay - i.e, I make sure every sentence is perfect. This way, you build a buffer. People forget that even though there's weightings, if you get 80% in all your assessments, you get 80 for the unit. Why, then, not ensure that you get more than 80 in the small, easy ones, so you've got a buffer come major essays and exams? In a lot of the exams I've sat, I've only needed 50%-75% on them in order to HD, which is a huge advantage. Why? Because I'm unhealthily obsessive. This quite literally isn't intelligence. It's obsessive discipline. (I'm not being one of those people that's all like "i'm totally not smart I just work so hard". I am smart, but I also believe this 'fiendishness' is more conducive to a system where marks are based more on habits than intelligence).
Like, I look at people that don't hand in assessments worth 2.5% and feel like I'm going insane...
did I really just see someone ignore a free 2.5%? You would be surprised by how careless a lot of people are... So my first tip is just be overwhelmingly conscientious.
How I study for my Arts degree... I go to lectures, absorb as much as I can without looking at my phone or taking notes, then I go to tutes and discuss as much as I can, and I make sure I do my readings and then I google extra stuff to get a broader, but not necessarily much deeper, understanding of what we're doing in class. So I see the where the content fits into a particular puzzle, which makes the content 'click'.
That's about as much as I can say about study habits... Really, they're just dependent upon the given pattern of assessments I get given throughout the semester. My study habits are like chess moves... I'm not sure if you're familiar with game theory decision making but that's sort of how you should approach uni. Emotionlessly and logically.
I make to-do lists and work through them, which I've always found better than schedules and which is conducive to the "work whenever you want" nature of uni. If you have a to-do list, then you can just work through the to-do list and that's all there is to it.
Everything I've just said probably tells you about how I manage a (very semi) semi-active social life and extra curricular activities... If going out would compromise my marks, I don't go out. If going out would benefit my marks, I go out.
Okay, so things aren't that morbid. The first part is definitely true, and I just go out when I feel like it, which isn't too often. I normally just relax at home - I certainly have the time to go out if I wanted to though. Essentially, when you're psychotic enough about it, you should burn through your to-do list pretty quickly and have a fair amount of spare time. When you're on top of uni and focus on it as your first priority, it's actually pretty easy. Again, I'm not being "one of those" people - but if you don't have a job and all you do is study, things are simple enough. In Arts anyway. The issue a lot of people have with uni is that they're in a situation that FORCE other things - like work - to be the top priority, and that's when the type of conscientiousness required for consistently high marks becomes tough. It's just shit, really, because some people just have to work and can't afford to focus on it. The other side of that coin is people who COULD focus on it but just don't care enough to bother. It's actually a pretty small minority that are nuts about their undergraduate marks... and, spoiler alert... they're all in Biomed. So, "how do live life and uni?" --- focus on uni and live life in the time you have remaining - which should be sufficient given you do the first task right.