1) Go to a target/semi target school
2) Do well in school(3.5+)
3)Network with alumni/firms
4) Learn how to interview and answer technical questions
5) Gain some experience prior to your junior year(networking or schools resources)
6) Ace OCR during the fall of your junior yr. with help from your network
7) Don't be an idiot and screw up a return offer during your junior year summer
Congrats, you just landed a job making over 100k/year in investment banking.
On a serious note, doing well in school and utilizing your resources really can make life a lot easier. If your school doesn't have a big presence in banking/consulting/AM/HF/PE or whatever you want to do, send anyone an email or phone call to discuss their past, what they do, and what tips they have for someone in your position. Obviously you won't get a lot of responses,but all it takes is one informational interview. You aren't asking them for a job directly at first. Finance people love talking about themselves, take down info and make sure you request something at the end of your informational interview like if they know any other people you should talk to. Stay in touch discussing your future endeavors or just talking about the market or something relatable. When the opportunity arrises at that firm, let that person know and things should tilt in your favor slightly.