Advise for a rising junior

As you may have gleaned from the title, I am a rising junior and I am looking for advise regarding investment banking. I am looking for any and all advise/ criticism as I am trying to get a banking internship next summer. I intend to start preparing right away.

I go to a top 25 Liberal Arts college and I am a Math and Economics double major and a Computer Science minor. I expect my cumulative GPA to be around 3.75 by the time I send in my application for next summer. As far as experience is concerned, I worked as an intern for a local boutique investment bank during the past school year. In addition to this, I have spent two summers working as a research assistant for professors in the economics department. I am also in a varsity sports team. I would really appreciate it if you could let me know what you think about my experience, gpa, etc. Please let me know where I am lacking and what I could do to improve over the next year or so.

I also want to point out that I have almost no experience with financial modeling. I have not had the opportunity to take finance classes since our college does not offer them. The only two classes that touched on finance were principles of accounting and partial differential equations ( I did some work with the Black Scholes model). Are interns usually expected to have a good understanding of finance? If yes, can you please let me know how I should self study?