The class of 2021 can stand to be more optimistic than the class of 2020. Employers plan to hire 7.2% more college graduates this year compared with last year, according to a survey with 207 respondents published in March by the National Association of Colleges and Employers. Job interviews are more high-tech than ever, and many remain completely virtual. But some imminent grads have been approaching their job search in a more old-fashioned way: networking.

“You get a lot of jobs not through the front door, but a side door,” says Gorick Ng, an undergraduate career adviser at Harvard. “That’s especially true for entry-level positions.”

Many jobs are still not being posted at all due to companies’ ongoing uncertainty about the future, he says: “That makes networking even more important than it was before the pandemic, so that you can find out what positions might be available behind the scenes.”

To identify good networking prospects, he counsels students to look for people who both share something in common with them (like their major or hometown, or a specific identity like being a woman in STEM) and are senior enough that they can make hiring decisions. For instance, he tells Harvard athletes to look at every archived roster available online for their sport and see if any former players are now working in a field or company that they’re interested in.

“When I get a message from someone who went to my alma mater, I answer 100% of the time,” says Jamie Szal, a tax attorney in Lewiston, Maine, and a graduate of Trinity College in Connecticut. “In my experience, alumni love students about to graduate from their alma mater.”

She adds that she feels a sense of solidarity with pandemic graduates because she graduated from law school in 2009, at the tail end of the financial crisis. “That was a really crappy year to graduate, and networking was crucial to getting my first job,” she says. “I think 2009 then is the equivalent of 2021 now… not that it’s way better, but people know what to expect in the second year of a crisis.”

Christopher Brown, a 21-year-old psychology major and football running back at University of California, Berkeley, says his school and coach have both pushed him to pursue virtual networking. This semester, he started meeting online with a career mentor on Saturdays. He was encouraged to reach out to professionals in the finance industry, where he hopes to work after graduating in fall 2021, both on LinkedIn and via his school’s “Golden Bear” alumni network.

He has so far met with professionals including a senior director at Qualcomm and a business coach focused on helping former athletes start businesses.

“It’s all on Zoom, and only 30 minutes at a time,” he says. “But it makes me feel way more prepared to enter the workforce at the end of this year.”

Some seniors sought out alumni to coach them through tough interviews, like Laura Polley, who is to start a full-time job at the consulting firm Guidehouse after she graduates from Colby College in Maine. She estimates that she spoke with more than 20 alumni of her college last fall to prepare for consulting interviews.

“They helped me not only with mental math and talking through my thought process for case studies, but also about how best to present my liberal-arts background and interests in an interview,” says Ms. Polley, who is 21.

She was able to connect with so many relevant alumni because she realized last year that she wanted to work in consulting. For graduates who are less sure about where they want to work, Mr. Ng, at Harvard, has several suggestions to look for high-growth companies and fields. First stop: Google. “I like to search for ‘fastest-growing company’ plus the city of your choice,” he says. “You can also look up startup funding announcements and see who recently got funding—they’re probably hiring.”

Another creative way to look for jobs is to look up the phrases “We’re hiring” or “I’m hiring” on LinkedIn profiles, and filter the results by first- or second-degree connections, he says.

Alongside the class of 2021, many from the class of 2020 are still on the job market, and they are still networking too.

Alena Hyde, a 23-year-old who graduated from Clemson University in South Carolina last year, has worked at a thrift store for minimum wage, dog-sat and worked two different internships since graduation. But she’s still hoping to land a full-time role in fashion buying. When the economy picked up this spring and more roles were posted online, she reached out to her personal network again for help.

“My dad’s good friend who works in human resources in New York, for example, posted on LinkedIn on my behalf to see if there were any opportunities for me in her network, and she has helped me edit my résumé,” she says. “I don’t typically send out cold emails, so I really appreciate that kind of mentorship and help.”

Even though hiring is rebounding strongly this year, there may simply be fewer full-time jobs to go around after the pandemic, says Blake Allan, an associate professor of psychology at the University of Houston.

“The labor market was already constrained, and the pandemic exacerbated that,” he says. “Young people graduating into this economy should be flexible about many different paths, instead of having one set career in mind.”

The Class of 2021 Goes to Work

Read more of the Journal’s coverage of the job market for new grads, and advice on landing an entry-level role.

Young Job Seekers Tap College Alumni Networks for Leads

Recent graduates struggling to launch careers during the pandemic receive advice, interviews—and offers.

Prep for Your First Job Search: A Two-Day Boot Camp

Practical advice from recruiters and hiring managers on what new grads can do right now to improve their job hunt

How to Dress for a Job Interview

“When done right, your look isn’t the first thing your prospective employer notices,” says Dena Giannini, the style director for British Vogue. “They just notice that you are polished and possess an air of quiet confidence.” Here’s how to pull it off.

How to Negotiate Your Salary

Salary negotiation is an art, but there are proven techniques you can use to get what you want.

Catching Up With the Class of 2020

The Class of 2020 was primed to enter one of the most robust job markets in history. Instead, they faced one of the most challenging job markets for young people in decades. Things are looking up now, though.

Write to Krithika Varagur at krithika.varagur@wsj.com

Corrections & Amplifications
Rebecca Moser is to graduate from Baruch College in May. An earlier version of this article incorrectly said she was to graduate in April. (Corrected on April 30)