Disclaimer: I am an IMG and am not too familiar with how first- and second-year medical education is carried out in the US.
I started studying for Step 1 about halfway through my second year. Like the poster above, I have heard many people talk about Gunner Training but I don't even know how it works. These are a few random tips that worked for me:
- Use First Aid as a general outline, to get a "feel" for the system/subject and to know what to focus on, preferably even before you take the course. If you can, read a bit. Simple summarized review books may serve as introductory texts (I used Secrets for Step 1, which is very very simple and lacking in information, but it gave me a base on which to start building my knowledge. There's books like first Aid Basic Sciences, and the FA Organ Systems which may serve as texts, but I don't know whether they're any good.)
- UW or Qbank may be a good investment, but these may be very expensive if you have to pay for a long subscription that will last 6-12 months, it would be great if you could start one of these early, but I don't think it's 100% necessary - you can save it for the last two months or so
- I would recommend non-online question books for practicing: Pre-Test series is really old and outdated but can be found pirated online or bought used for very cheap (a friend of mine bought like 20 books for $25 used on Amazon). First Aid has a Q&A. Kaplan has a Qbook. Lange Case Files has select cases with discussion and a couple of questions for each. Stuff like that. All you need is something you can start practicing on and that you can use for general studying before you pay for a "real" question bank
- When you finish a particular topic/system/subject, go over First Aid again as a final review, then do as many questions as you can, this will help "seal" the information.
- Study for your classes and seriously try and do well. My classes were terrible but I still paid attention and studied for my tests (and later on in my clinical years, really put effort into my rotations). This helped me a lot, see the next point:
- Build a good foundation of medical knowledge - read articles, stay up to date on medical news, look up EVERYTHING you don't know, even things you hear on House/Grey's Anatomy/Scrubs if you watch any of that stuff (wikipedia is actually really good for quickly looking up diseases/drugs).
For example, I did all this for my patho courses in my second year and I barely had to study ANY patho for Step 1 (this was two years ago and I took my test last week)
Your mileage may vary and like I said I don't really know what most US students do, but in short - study a lot, do questions, expose yourself to Step 1 level material early and you'll do well and won't have to study that much when test time comes. If you do it just right, all you'll have to do is skim First Aid and do many many questions.
Hope this helps and good luck!