The best thing you can do is do your best with what you can control and keep up with the changes as they happen so you can better prepare as you move forward.
Control what you can, not what you can't.
Go into ROTC with a VERY open mind. If you've done JROTC, etc in HS, don't think you know it all - cause you don't.
... I wouldn't focus to much on FM's your first year - you definitely don't want to be "that guy." If you are going to look at specific manuals - you'll want to know AR 670-1 (Wear and Appearance of Army Uniforms and Insignia) and ADP (start with ADP, then move onto ADRP) 6-22 (Army Leadership - this will be much more meaningful than a couple of manuals that talks about super Hooah tactical movements).
You want to set yourself apart? Being a leader - but more importantly, understanding how/why/what makes a good leader - is what separates you from your peers; not how much tactical knowledge you know. That will be astronomically more important for your leadership development than learning about tactics. Don't worry about tactics, you'll learn it soon enough, and it's not some super complex thing either.
But if you insist on looking at some of those super Hooah stuff, the Ranger Handbook is a very nice place to start. Do yourself a favor though - if you do pick up a copy, try to get a small "pocket" edition of it (and by small I mean like a 6x9" copy that can fit in your ACU cargo pocket. It can/will come in handy when you go on FTX/LDX's. I use it from time to time as a quick reference. (You'll thank me later)
Oh and while we're on it, please take the time to understand the form CCF 104-R (academic plan) ... people ALWAYS struggle with that. Junior year, people still struggle with it.....
Listen to what everyone else as additionally mentioned. Basically, as long as you go in with an accepting attitude and not a "no, I'm right, you're wrong" attitude, it's hard to go wrong.
Best of luck.