10 things I've learned as an intern:

1.) Always come on time. Some of the most important events break news in the morning and not only that but coming on time helps you to better prepare yourself for punctuality in the real world. "If your 5 minutes early you're on time, if you're right on time- you're late, and if you're 5 minutes late don't even bother coming." 
2.) Learn how to take constructive criticism. All the adult figures at your internship are there to help you.
3.) Speak up. If you dont understand something or have questions don't hesitate to ask. Its better to ask too many questions than to not ask enough and feel completely lost.
4.) Always double, triple, and quadruple check your work. Nothing is more unprofessional than a grammar or punctuation mistake. Everyone makes mistakes but try your best to limit yours down to as little as possible.
5.) Carry a notebook or agenda. As an intern, you'll get an abundance of tasks so carrying an agenda helps you keep track of them.
6.) Pay attention to deadlines. Always try your best to finish an assignment before the deadline. Think about it this way: the earlier you finish your assigntment the more room you have for mistakes. Meaning, you'll actually have time to get it checked by someone other than yourself because you won't be finishing it at the last minute. Additionally, I like to finish things as soon as possible because if not it may slip my mind.
7.) Don't forget to take a lunch break. Sometimes you're so overwhelmed with work you forget to eat. Everyone needs those 15-30 minutes to zone out and re-energize themselves.
8.) Even when there's nothing to do- there's something to do. Pretty self-explanatory. If you don't have any work to do, someone else has work for you to do. 
9.) Make friends with the other interns. You aren't on this journey alone. Talk to them, ask them questions, become friends with them. They can help you alot more than you may think.
10.) Don't stress too much. This internship is for the benefit of YOU. It can only help you.