Some really nice tips via comerecommended.com.

1. Mistakes are inevitable – what matters is your reaction. The company didn’t hire you for your expertise. Say you mess up on an assignment or upset a client; instead of getting defensive, show your boss you both regret what happened and learned from the experience. It won’t only save your job, but keep communication between you and your boss open.
2. Don’t be afraid to ask the seemingly simple questions. Your co-workers are going to throw a lot of information at you that after a few years of working there seem basic. Don’t be afraid to ask them to slow down or repeat themselves later. By learning how to get tasks done during the ‘honeymoon’ part of your internship, your job will progress a lot more smoothly in the long run. 
3. Be proactive! Couldn’t stress this enough: during down time at your job, stay proactive and ask co-workers what you can do to help them. It not only keeps you busy and learning, but you teach yourself how to be helpful around the office later without asking your boss what to do. 
4. Be eager to learn. Similar to keeping proactive – if you take care to show your coworkers you are eager to learn, the more likely they will let you sit in and help with their more interesting projects. 
5. Take notes and sit in meetings. With the loads of information that will be dumped into your head, take notes of what’s happening to jog your memory later. Also, don’t be afraid to sit in meetings (of course ask first)! Chances are your boss will forget to mention some things, and sitting in on meetings can help you learn the office dynamic and pieces of information your boss may have forgotten to share.

I have to say that out of all of these #1 stands out the most.  When you’re new and don’t know much things will fly at you and mistakes happen.  You’ll probably be the one making them.  Learning how to accept fault and move on to correct it is a skill few have.