Start early, be determined, and have a lot of patience. Tell them why you are coming so they can prepare themselves for your questions if need be. Their time is as valuable as yours, so make sure to be on time. People love to talk about themselves and their work, and you will gain valuable insights into both if you just listen. For example, a theater major might learn a lot from a business manager in terms of keeping things organized, on time, and pulling many things together.
Any experience is better than nothing.
Check if you can contact your mentor in the future with questions, and ask them if there are other people with whom you should speak. Try to maintain regular contact when appropriate. If you find that the internship is not to your liking, then you have the freedom to leave. Having a good mentor can be the key to having a good internship.