Searching on LinkedIn is a great way talk to someone for at least an informational phone interview, if not a coffee meeting in person. If you explain why you're interested in what the contact does, what you're studying in school, and a few questions you'd hope to learn from a phone conversation, most people are very open to mentoring and sharing their experiences and advice with you.
Joining a young professionals community or attending one of their career development or recruitment events is another good way to interact with others in different industries with various experience levels. Members of those types of groups and events are also usually there to network or learn, so it's a great place to meet a contact and ask for an additional opportunity to ask them more.
If you have an idea of the type of career you'd like to learn more about, don't be afraid to leverage your existing network to get a contact's name (such as coaches, guidance counselors, relatives, friends' parents, business owners in your neighborhood/community). If you are polite, respectful of the contact's time, and eager to learn, most people will be very willing to give you 30 minutes to answer your questions and to share their insights and expertise.