Every student should have a target list or dream list of employers they want to work for. Normally, I coach students and have them put together these lists when they are actively applying fo rinternships, but you should have one all year round - if you are applying or not. You must constantly be reminded of your future goals and keep yourself informed and up-to-date on the company of your dreams.
Brands and employers are spending TONS of money to make sure they have a social media presence. They are doing this because they WANT to engage you, they WANT to start a conversation, they WANT to hear what you think. Go to the website of each of your "dream employers" and try to find the Facebook or Twitter logo. You can also google "company X on Twitter" and find their profiles. Again, the majority of employers do have these profiles set up.
Following these brands will help you identify with the company culture, tone, and stay in the loop of their programs, career opportunities, and news feed. I would also encourage you to comment & tweet. Get yourself involved with the conversation. Send your questions, they pay someone to answer them! Communicate directly with the employer of your dreams - it doesn't get much better than that.
One more note to add is that last night during #internchat, I was asked about employers following students back on Twitter and potentially seeing negative things or inappropriate things. No matter what your age - student or not-social networks are not a place for negativity or inappropriate content (pictures or posts). Make sure that before you start following employers, you clean up your pages and make sure that your page is a representation of your personality (the best side of your personality). Delete anything that you might have questions about - it's probably not okay.