IB advice to sophomore. Thanks for your help.

I'm a sophomore at a top three school with a 3.9 gpa, 2350+ SAT, Econ major. I applied to one (and only one) of the top BBs, making it to the superday. However, even though I thought I did very well in interviews, I heard via email a few days afterward that I didn't land it, so I obviously didn't do well enough.

My guess is that it was because even though I'm an Econ major I don't know accounting and/or I have no direct experience in finance. One of the other Superday candidates had already worked for the company in question and most of the other were Finance/Accounting majors rather than Econ. My guess is that put me at a disadvantage even though I came from the most "prestigious" school.

First of all would emailing one of my interviewers or the HR person about how to improve my chances be inappropriate? Who should I ask? Secondly, do you think I should try to work in a finance-related job this summer to improve my chances or is any impressive internship (even non-finance) okay? Finally, do you think that taking an accounting class this summer makes sense? I'm in a financial markets class now, so I'll obviously have much more knowledge by the time I do this again, but I still won't know accounting details.

Thanks for your help.