I think Vlad is spot on here - I completed an internship last year and found that i spent 80% of my time making powerpoints.
I would just take some rest and make sure that you take care of all “normal” life things you can before the internship so that they do not become a distraction during this key experience (e.g. ensure you have all your shirts pressed and starched, ensure you have enough shirts, take care of bills that are not due yet but will be due during internship, etc)
hope it helps,
Preparation is extremely dependent on where you are employed and what your job is. It also plays a role in which company you complete your internship. All in all, I can only advise you to have a good night's rest and to recover the last 2 weeks so that you can start the internship full of energy.
I recommend to prep Financial Modelling and Power Point.
1) Financial modeling - the best course I know is Training The Street. Take Financial Modeling, Valuation, Maybe LBO
2) Power Point - Google for MBB presentations and try to replicate them. Search for tips and tricks in books / internet in parallel. Plus read "Say it with charts" and "Pyramid Principle"
And finally - take some rest before starting your job;)