Read ahead of time. Keep up with your chapters. form study groups. make friends. practice. show up on time. turn your phone off during class, to minimize distractions. volunteer to be the first person to do any and all hands on skills.
Things to pay special attention to: PATIENT ASSESSMENT. its the basic foundation of medicine (EMT/Paramedic/nurse/doctor). if you can't do a decent patient assessment, than it doesn't matter if you know everything else; if you don't know when the patient needs it, all the interventions are worthless.
Everything in the class is important to pass the class, so you need to know everything, even if your instructor doesn't mention it. if it's in the book, it's fair game. if it's in another book, it's also fair game. You might not need it in the real world, but it might be brought up during exam time. If you don't understand something, ask.