OCS
The career fairs are not very helpful, since there are many people at fairs and sharing resumes. However, OCS has several resources on engineering-specific career pages: general, bioengineering related.
Career fairs can be helpful; a former facebook policy intern got their position through connections made at a CS50 career fair. An intern at Tesla got their first college internship through the i-lab startup career fair.
Additional tips
Connect with people on Linkedin. Harvard alumni/upperclassmen are great, but they don’t just have to be Harvard affiliates! Most people are excited and happy to help interested students. By contacting people on Linkedin, you can sometimes get an interview for a job before the job posting is even up.
Intern at biotech startup Emulate got the position by reaching out to a senior scientist on Linkedin.
Keith Karasek, the SEAS Director of Experiential and Career Development, can help guide you and connect you with upperclassmen who may have worked in a field you’re interested in, or at a company you want to intern at. See here for more information about scheduling a 1-on-1 session with him.
Research at labs. Students can cold email professors and express interest to get research opportunities! Start by looking through the SEAS website and the news to see what kind of research you're interested in. From there, find and email a PI/postdoc/PhD student with your resume and ask to set up a meeting. Research offers a lot of general flexibility, since you determine your own schedule (5-20+ hrs part time).
Intern at SpaceX and Waymo got their first internship at international company Parrot by giving a tour of their research lab to the CEO of Parrot. They also interned as a sophomore at Apple in Japan, an opportunity that may have been difficult to get as a sophomore in America.
Bioengineering student had a discussion about their academic interests with their lab PI—this led to their PI introducing them to a contact at Novartis, where they were offered a summer internship position.
Freshman/Sophomores
Conduct research through various grants/programs (PRISE, HCRP grants, etc.)
Freshman Intern at PRISE reached out to a professor to find a project before they even got accepted to the program. The intern applied to PRISE with details of the lab already set (possible projects, which lab/PI, etc.)
Go to an international company/startup. They are more likely to hire younger college students, and it’s a great way to gain a study abroad experience while also exploring your career.
Environmental engineering: All Ivy Environmental and Sustainable Development Career Fair, a large career fair hosted in Columbia involving Ivy league recruitment.