Is there anything in particular that you want to know about? You don't need to be nervous - just stay organized and you'll be fine
I guess my biggest piece of advice would be to have an outlet outside of school, some sort of hobby you enjoy doing. I remember when I started that I was under the impression that I would have to say goodbye to everything I enjoyed doing, but it's actually very important to relax and take breaks in between studying to help you refocus when you return to the books. That's not to say you should go overboard and not spend enough time studying, but it just doesn't do you any good to study 24/7. I would also recommend simplifying your life outside of school. Make sure you have a peaceful living environment (make *sure* you get references from landlords if you are not living in the student apartments - I had to deal with a miserable situation that distracted from my studies and caused more stress than school itself), don't overcommit, and make sure your family/significant other understands what kind of commitment you are undertaking so they don't take it personally when you have to spend Friday night with your Netter book instead of him/her.
I don't necessarily think subject matter of med school has been a lot more difficult than undergrad, but it's a lot more information at a quicker pace, so that's why it's important to stay on top of it and not save all your studying for the weekend. Something else I had to accept is that it's just not possible to know everything, so you do what you can and hope there are questions on the stuff you know! You might have a lousy test grade every once in a while (the first block exam is usually very humbling
) but it's not going to break you, so don't stress over it. It takes some time to figure out your study style and once you find your groove, things are smoother from there. I think that's why in general people say the second year is easier - there's more info and tougher content than the first year, but you finally have figured out how to study and what to expect.
Let me know if you have any specific questions - I can at least give you my two cents!