I made the mistake of taking those last months of freedom --- and promptly fell on my glutes royally during intern year and am still trying to shake the perception (not without a grain of truth) that I don't know WTF I'm doing......
So, what would I do differently?
1) I'd make it a point to read the AAFP journal, if not cover to cover, then at least the 3 major articles they have in each edition -- and now you need to focus mainly on workup and treatments...esp. treatments...know the names, dosages, course and options...
2) I'd know the general workup/treatments for major things in IM -- like CHF exac, COPD/asthma exac, DKA/hyperglycemia, ascites, cellulitis, osteo, MI, intractable diarrhea, pancreatitis....and I'm sure there's some others I'm missing....again, know the lab/imaging workups and treatments...more importantly, know/understand discharge planning...what are the criteria to get these people the heck out of the hospital?
3) Review OB, peds, surgical knot tying, suturing, electrolytes, blood gases......
That should be enough to keep you up at night for a while.....and then start getting some dedicated sleep time...figure out what you NEED to stay fresh, what you can get away with for a day or two with 'catch up' in a few days....tone down the caffeine, you'll ramp back up later....if you're overweight, lose it now, go in aerobically fit so you can keep moving....
Good luck....everyone, some more than others, cries like a little girl....but everyone, with few exceptions, makes it through....
Also, practice your presentations before the mirror -- it's no longer about reporting/droning on about information that you've discovered...now it's about -- the patient has X based on this, I'm presenting this information to let the attending know I've thought about/ruled out other big bad stuff and since I'm reasonably sure it's this, here's WTF I'm going to do.....practice that until you can present it with confidence and keep it 'tight'.....stumbling around, skipping around, answering, "I didn't think about that" or "I don't know" will get you hammered and shark attacked...for quite a while.....don't ask me how I know....
Also, the Shark Talk --- If one of your colleagues has attendings/upper levels/fellows circling them like sharks, either verbally or whatever, everyone else stay the hell away so to speak. If you get involved, you'll get bit also....it's over faster...once they smell chum in the water, the feeding frenzy is vicious.....and you'll bear the scars.....
Good luck....