Throwaway account to try and keep identity as anonymous as possible. Going to share my experience as I'm starting my BB SA gig this summer in a top coverage group, doing it coming from a non-target school with an average GPA (~3.5).
I came to school to study something arts-related, totally different and very irrelevant to IB. Partied my butt off first semester and had a pretty crappy GPA (~2.9) for my freshman fall. Pledged a fraternity and ultimately changed my major to finance and math. My family has run a small business for decades and decided to explore a sell-side, which was a perfect intro into the world of investment banking. I started reading anything/everything I could get my hands on, subscribed to all the deal emails (Term Sheet, Pro Rata, etc.) and started trading a personal account. Joined the investment club on campus, got my grades up a lot. Started networking my freshman year and used the handful of alumni in banking as well as just any brief connection I could find.
Freshman year IB internship
Found a guy who ran a boutique investment bank near NYC who went to a completely different non-target school and started talking to him, which in turn led to him taking me on for a (paid, somehow) internship for my freshman summer. We meshed very well and honestly I strictly got this for putting myself out there showing I was willing to learn and work hard. He asked me back for the next summer as well.
Sophomore MM IB
Leveraged my prior boss' connections to try and start networking early as the process for SA recruiting is incredibly accelerated - after a few coffee chats with an MD at a solid MM shop, he offered me a spot to intern for two months alongside the SA class (who were all a year above me). I didn't really do much or contribute anything, but it led me to automatically being considered for a superday and I was able to land an offer here for the actual junior summer SA spot. Again, non-target MD who saw I was willing to learn and had some prior experience that I could speak to.
Landing the spot
I had been reaching out to probably 20 bankers at (insert top BB here) across different groups before actually getting thrown into the interview process. Had a HireVue during the summer 2017 and ultimately was flown from school for a superday last September, coincidentally having this superday the day after my other superday from my last internship. I had spoken with MD's, associates, VP's, analysts - all in all probably had cold emailed and gotten calls with ~10 bankers, a handful were in the same group and were able to chat about me and I think helped me out. Came in for the superday, knew all my technicals (IMPORTANT), and just honestly showed my enthusiasm as best I could. An MD interviewing me asked how I'd gotten in there (and I had spoken to several people on his team) and told him just by talking to guys in his group - somehow impressed him there. Eventually got placed after I accepted the offer in one of the best groups across the street.
If you go across this site you will find MULTIPLE different accounts similar to mine describing story after story for non-targets getting into IB positions. Networking is literally the only reason I was able to get a spot in addition to having relevant experience to back up my story. Anyone can say they "want to do IB" but people like to see that there's a tangible, chronological timeline for why you actually want to do it. Make a spreadsheet, used LinkedIn like crazy, and put yourself out there. Networking is so critical and don't shy away because "they're an MD, they won't respond" or "they're an analyst, they can't push me through." Believe it or not, just about any banker (except for an analyst who's been there for ~3 months) can recommend or shoot your resume to HR.
My cold email strategy
More often times than not, bankers may not even respond to your initial email and a week later you'll somehow have an interview. That in mind, I reached out to ~400 bankers, research analysts, sales and trading people cold with the following methodology: if you went to a non-target school, you were on my list. Why? They'd probably understand the grind of networking more than the banker who was a Wharton UG/Harvard MBA who had 100's of kids knocking on their door. Don't hesitate, what do you have to lose? The worst response I ever got (once) was a "we're not hiring, pls stop emailing." Going off that, don't be insane in these emails. Be casual but straightforward, I sent about a 4/5 sentence long email introducing myself, my major, my prior experience, and then asking to hop on the phone/if they had any free time to chat about their experiences and then wrapping it up with a "attached is my resume." After a week if they hadn't responded, I'd ping them again (obviously no resume again). A week after that, once more. 3 emails total before crossing them off my list - and believe me, there were tons of people who didn't respond.
Cold email success rate
I'd put my hit rate in the 20% range (which is awesome, but it's 1 in 5 people emailing me back, often times not having time). Keep track of when you're emailing, if they respond, make a calendar to track when your calls are. Have it down to a tee because it's super easy to get disorganized with networking and you need every connection you make, cold or not.
I probably should've led with this, but start EARLY! High school is insanely early (there's a couple posts on here about high school internships, relax). But if you really want to make a jump into IB it's best to start networking freshman year. Get your name out there, learn some, start familiarizing yourself with technicals. Don't be the guy who worked incredibly hard to get a final round interview just to screw it up because you hadn't spent time studying technicals (it's not as daunting as it sounds). Apparently recruiting is even earlier for 2019, so that means you need to keep yourself ahead of the curve.
Answering technical interview questions
Technicals are so crazy - there were superdays I didn't even get asked one what is WACC or walk me through a DCF question, and there were first round interviews with different banks asking me about PiK interest. Obviously you want to come in over-prepared, the easiest way to ding any candidate is if they aren't technically sound.
The three best resources I used was the guide on this site (which is the only one I paid for), the 400 M&I question guide (which you can Google and it shows up as a pdf), and then a M&A and LevFin heavy guide that an alum sent me (Rosenbaum & Pearl, not sure if it's free otherwise). Again, I interviewed also across other BB's, EB's, MM's, and across divisions (ER, S&T). I had 3 superdays that were all for IB, and probably a dozen other first/second round interviews ranging across levels of finance. I had my story tailored pretty well for each (important), and granted a lot of the questions I got for technicals in IB were the same for ER, difference being ER/S&T asked more markets based questions.
I just studied, everyone has their own methods. I would have my sister ask me questions in a mock interview type setting just so I knew them cold. A huge part of these technicals (especially if you don't know) is just the way you think through them. I got a question in this BB I got an offer from on the superday about leverage and I didn't know the answer, but when I slowed down and worked through it out loud I ended up getting it right. Sometimes that happens, but if you have a clear and logical process then you're better off then mumbling or guessing.
Putting in the time and effort
My parting piece: if you want it, show it. So many people on this forum I've seen complain and whine about "missing the boat on IB" or those "IB or bust" posts. It really isn't the end of the world if you don't get it, but even moreso: put the time and effort in! No one will feel bad for you, no one will do it for you --> I spent 3-4 hours on the phone a day talking to people and another 3-4 sending emails. You HAVE TO pull out all the stops and work for it because no one else will. It's the toughest industry to break into for a reason!
Thanks for reading and happy to answer any questions! This forum's been incredibly helpful and wanted to give back in any way I could.