What subject are you studying? Maybe there are people here in the forums who can help you cuz it really depends upon what you are taking.
I'm now going for a 2nd degree in Bio and I was an Art major. I'm taking Calculus after 4 years without math and in bio lab I had to cut a pig open to study its organs. I also failed a quiz in bio lab cuz the woman talks so fast and everything she talks about doesn't come in the lab book. And I can't take note cuz I think too much and suck at taking notes, plus I missed the first class cuz of flu. At least I made friends in class who are willing to help me and I don't plan on giving up so easily.
Try joining a study group or something. Make lots of friends and study together for the test and do your hw together so everyone benefits.
Don't worry, the more you panic you'll just lose your mind and whatever you just spent the last hour studying.
Whenever you start to feel like your stressing out, stop everything you are doing for 5 mins. to breath. Take like a mini time out like we would do in pre-school except on a nice comfy chair. Clear your head of everything cuz college ain't worth losing your mind over.
College is suppose to educate you... not kill you for a silly piece of paper with a grade on it... you are worth more than the paper cuz one I can get anytime, and the other...well lets just say "There can be only one." So don't overkill yourself. Plus you can't get a degree if you go mad or die...just keep that in mind
Once your head is clear, write down on a sheet of paper at least 5-10 things you need to study about, or write down some names, terminologies you need to define, whatever that comes to mind. And try to break down your work load into smaller study plans so to help you focus on searching your material for those simple key things you just wrote down, which makes the work way less overwhelming. Your memory will help you fill in the blanks when you start going over things that are more familiar. Once you're done with that group you repeat the process till you have learned what is needed. Chances are at least this way you'll at least know something definite for the exams. Though 70-80s ain't bad grades....you just need to study a bit more. You're new to the college scene, so let me say you don't need anymore drama and stress, then what you already have. You'll just burn out and get sick quicker. Take good care of yourself and good luck with you school work. Your a responsible adult now, you can do it and get the job done. And then end the semester with a small celebration on your behalf for getting through round one.
Don't worry... you can do it. Just do what you need to do and don't forget to take care of yourself first.