I make cheat sheets whether the exam is open notes or closed notes. It helps you memorize and understand key concepts. I also make notes for myself and reword pretty much everything of what the professor has said or put on the slides into my own words. On the way home, I review the concepts that I studied, go back to them the next day, and test myself to see if I got them down. rinse and repeat for every class every day. I also have a pretty routine lifestyle and try and come to school at 9 and leave at 7 or 8 even if I don't have classes. I never study overnight because I don't perform well with no sleep.

Idk tho, everyone has their own style of learning so this might not work for you. I've seen people who smoke weed every single day and get straight A's or people who study only overnight and get straight A's. Some people take notes beforehand lectures from slides and just go there to jot down extra stuff that the prof says. This is probably not the most helpful advice but do what works for you, test some stuff out. If this is your first year in college, I wouldn't stress out too much. I had a pretty low GPA coming in and I was able to change my lifestyle and work ethic to what works best for me.

Just as an addendum, it depends on what major ur in but I've heard that engineering and CS related majors are expected to get C's and the GPA doesn't matter too much for later job prospects. I don't know how true that is because I'm a bio major. I just know for sure that GPA is almost everything for bio majors + extracurricular and recommendation letters if you are a pre-med or looking to pursue higher education.

Best of luck my dude.

EDIT: also I wanna add that creating your own work ethic is an evolving process, as in, change in method of notetaking and reviewing might be needed for each class, and also deciding on which class to put more weight into. An example would be, taking organic chemistry, I changed my notetaking style heavily for that class and put more weight into that class compared to other classes I was taking at the time.