At the beginning of your career, your goal should be to get an entry-level job. Maybe you have a really great internship supervisor who can guide you through the process, but most likely, you’re on your own. Your strategy shouldn’t be centered on finding that one mentor, but rather, on making as many connections as you can to secure a great entry-level position.
Once you’re working, you may find a natural mentor in your boss or someone else in your department/company. There’s no need to make this official -- we’re often asked the question, “How do I ask my boss to be my mentor?” and our rule of thumb is that if they want to be your mentor, it’ll be obvious from the way they allow you to grow in the company or encourage you to apply for outside jobs that meet your long-term career goals. (It should go without saying that this will only happen if you excel at your job).
If you can’t find a natural mentor at your current job, don’t fret -- you’re actually in the majority. But don’t try to inorganically rope someone in. Instead, have informational interviews with people at companies you want to work for or in roles you aspire to fill. Learn from them. Follow up with them to maintain the relationship. Again, don’t ask directly for mentorship -- you’ll know it when it’s happening. And if it’s not, that’s okay, too. Mentoring someone can be a huge time and brain-power commitment, so just because your great contact at your dream company doesn’t fall into that role doesn’t mean they’re not going to help you otherwise. Your contacts will likely be open to passing your resume along for jobs, even if they aren’t up for frequent emails asking for advice.
In fact, it's not smart to put all of your eggs in one mentor’s basket. Everyone’s career path is different, so your would-be mentor’s advice can only go so far. The more people you learn from, the more likely you are to see alternative paths to your dream. Plus, one phone call advocating for you for a position is never as good as three -- you may be better off building multiple relationships than one really intense one.
As your career grows, you will eventually find your most trusted allies. Maybe it’s one mentor, maybe it’s a peer who came up with you, maybe it’s both or multiples thereof. Remember that Harry had Dumbledore, Hermione, Ron, Sirius, Lupin, and the whole Order, and he still had to face Voldemort alone in the end.