Obviously, for the competency questions, have a few good answers lined up. (Look up the STAR method if you're not familiar with it already.) Don't neglect this part as I think it's crucial.For the case study I think it's important that you justify your points. I felt this was more important than actually hitting the right answer. Give your suggestion and your justification. The partner will always question your decision with the flipside of the argument, but it's important to stand firm, and give your reasons confidently rather than saying "yes, yes I suppose you're right...".As for the group exercise I think it depends on the kind of person you are. There are probably some dead cert ways of succeeding at this, but beyond the obvious, I don't know them.Finally, commercial awareness is very important and I think it would help if you had a preferred industry in mind and some knowledge of how that industry works to show how you could add to the knowledge pool of that area. I should stress that these are just my methods which although mostly sucessful have sometimes let me down! I'd be interested to hear any criticisms or other ideas.Otherwise good luck, at the very least it will be hugely beneficial practice.