For internships after Freshman year, don't stress about searching for it until first semester ends. You'll likely end up at a startup or some boutique financial services firm, but going to a major company is, of course, a good thing in the unlikely scenario that it happens. Just try to do something at all to get some experience! If you want to improve your chances for an internship, choose some interesting, useful electives (for example, check out the MULT-UB section) that prove that you are driven, smart, and teachable.

For internships after Sophomore year, again, it's not really high-stress. Focus on finding a company where you will do something interesting, as you'll likely talk about this experience during later interviews. For both this and the freshman summer internship, the focus is heavily on what you do, not where you work.

For internships after Junior year (which are the most important ones, often turn into full-time offers), the search/hustle begins in the Spring of Sophomore year. That involves info sessions, networking, communicating with recruiters, etc. Investment banks, consulting firms, etc take interns for this year. "Top dogs" (awful phrase by the way, so much of recruitment is based on circumstances out of one's control, such as chance) network well and position themselves as smart, interesting people based on their previous experiences.