If you don't have any accounting knowledge whatsoever, best thing you can do is just pick up any accounting text from the bookstore (doesn't matter which one) and get a basic handle on the "logic" of how accounting statements work.
Accounting more than any other subject frustrates MBA students because it's about as tedious and confusing as filing tax returns (by yourself). And as a result, it can be a needless time sink when you're trying to figure out why your journal entries and T-accounts don't make sense.
Especially for those from analytical backgrounds, accounting can f' you up because on the surface it looks like math, but really it's just a set of rules for how to organize different numbers.
Just my opinion - the more familiar you are with accounting principles and basics prior to b-school, the better your quality of life will be as an MBA student. While you'll have more time to focus on other subjects, network with recruiters, etc. your fellow classmates will be stuck banging their heads against the wall, ready to blow up their accounting textbooks trying to understand why debits can be addition to an account, and credits can be deduction from an account, and how that can then reverse itself as well depending on which account you're looking at.
The rest of the subjects (finance, marketing, etc.) are fine - most of the time, these subjects are a bit more interesting and not quite as frustrating (even if it's not always "easy" but at least not as tedious).
Follow me on Facebook