It's a good time to be asking that question. I wish I'd thought about where I'd end up during my first year.Get top marks in whatever academic field you enjoy most - it doesn't really matter which one it is, they just want to see that you've got a head on your shoulders. Get involved in a few extracurricular activities that you enjoy and that will provide some metric for just how excellent you are. At least some of those activities should be "different" - you don't want to be the 100th applicant who does debating.Try and make sure that this track record also reflects the qualities that MBB are most interested in, like leadership and innovation. You could trawl their websites for a list of these. The nice thing about the above strategy is that, if you change your mind about what you want to do, you're well positioned to do almost anything else and you've only spent time doing the things you enjoy.Note: you don't have to be particularly exceptional at any one thing if you can keep yourself in the top 5 - 10% of several fields at once. I got first class honours, ran two prestigious clubs, volunteered for a bunch of worthy causes and started a successful non-profit organisation. If you put those things together, they make me sound like I'll be a good employee. But none of these things is particularly hard to achieve.