"They say there's nothing to fear but fear itself. Obviously they haven't taken the IBH Physics exam as yet..." - former IB student
There's no getting around the fact that the IB exams are a distillation of two-years' worth of intense study and learning. That said, they're certainly not impossible to study for and really preparing for the IB can be an extremely rewarding process in itself. Here's what we recommend.
Look at previous years exams. This is by far the best indicator of what to expect. If you don't have access to previous years' exams, ask your professor and they should be able to hook you up. More importantly, replicate actual exam conditions and take some old exams so that you're comfortable spending upto 3 hours using your time in the best possible manner.
Memorize, memorize, memorize. For quantitative subjects such as math, physics, chemistry and bio, you absolutely need to memorize all the various formulas and standard equations. There are loads of different ways of memorizing, so explore options that work for you.
Structured thinking is a must for english, history, economics and language subjects. If you can learn how to clearly define and structure your thoughts, it's a huge plus and can not only help you be more focused in your thinking and responses, but it also makes it easier for the instructor/grader to understand what you're saying very quickly. Look at online resources on how to structure arguments in an essay and you'll get the general idea.