Hey, 19 here and in my 3rd year of university; id definitely suggest just not slacking at all, literally. Staying focused, taking great lecture notes and using as much resources as possible; for example, oneclass offers study guides, and lecture notes and assignment notes for classes; that are submitted by students of previous years who took that class, it helps a TON. Building relationships with classmates who you can depend on here and there for help and also building a friendship. Having a good relationship with ur prof and TA helps a ton as well. But definitely external resources including oneclass in helping with you're schooling and just for studying and understanding stuff.
Also, not overworking yourself. Managing courseload and work outside as well work surrounding working yourself as a person. courseload increases steadily as the years ago, and you should definitely limit you're hours in working at you're job. dont overwork you're self by giving into working a ton of hours at work as well as working on courseload. It'll fuck you up. Happened to me, thought i could manage, i couldnt. and also, leaving time to building yourself. School gets extremely stressful, and it mentally has an affect on you in university; id just have stable support systems to rely on when such problems arise, which hopefully they dont.
Textbooks. DONT BUY CLASS TEXTBOOKS QUICKLY. There are always PDFs online of textbooks, and iv spent so much fricken money on textbooks, even though pdf versions were available online for free. If there is non, id buy refurbished textbooks and ebooks to save on money if you're tight on budget just cause tuitions hard to really payoff at times and gets overwhelming.
Lastly, like i said with resources man, even talking to a school counselor when things get tough or for literally ANY PROBLEMS or something you're having difficulty in doing or understanding helps a ton. They help and find a way, its really good to take advantage of every resource possible thats provided in helping you, some people are hesitant and i guess shy away towards them.
Also, enjoy life man. you're first year includes some sort of froshe week, depending on where you are; and just the first week which includes campus parties, and extracurricular activities during the day that allow you to meet others. it is absolutely amazing to do this, cause many people you meet are usually always in you're class and first week was probably one of the happiest weeks of my life. It was amazing.
Hope university treats you well.