Relax and enjoy your first year. If you pay attention to any of the classes, make it physiology. At the beginning of your second year, buy First Aid, BRS Pathology, Robbin's Review of Pathology, and BRS Behavioral Science. If you think they'd help you, I'd recommend Clinical Micro made ridiculously simple and Lippincott's Pharmacology as well. Use FA to review all course material as you learn it in class, and use the other study guides to help you fill in the holes or help you focus on what's important/high yield. A review text's greatest asset is indicating to you what is clincally important and high-yield.
Whatever you do, begin your studying for the Step 1 at the beginning of your second year. This does not mean pull all-nighters like a speed junkie; just study the information you learn in class and try to retain it. That's a key point. So many people in my class study for the exams, and not the future. Once a given exam is over they think, "well, thank god i don't have to study that again until May" and then they perform a complete mental bowel movement. Why wait until a month before the step?? These people are then going to have to "re-learn" 30 test's worth of information again (yeah, you can retain some old material, but you can also lose a TON if you don't consolidate it over time). Start retaining material now and building upon your knowledge base, so that when your boards roll around, you'll hardly need to study much at all. You'll perform really well on the nbme's, and you should be a lot less stressed than your classmates come May/June.
Also, while you're studying second year courses, be sure to relate the diseases with stuff you learned your first year. For example, when you study GERD, review the anatomy and histology of the GI tract, along with the physiology and cell biology. Then add in the microbiology and pathology, followed by pharmacological treatments. It's kinda like reading a collection of short stories on the body, and it should really help tie everything together and get you thinking in more than one direction. If anything, that should really help you on the Step and in the hospital. Good luck!