Things I wish I'd known.
Learn time management & delayed gratification. This is the number one predictor of success in my experience. Yes going out with your friends is more interesting than working on your assignment; but finishing your assignments in a timely fashion so they aren't all due at once, and then going out with your friends is better. I recommend using Google Calendar or similar alternatives to keep track of your timetable both classes and other activities.
Read Never Eat Alone by Keith Ferrazzi. Your network is important to your success. If you're technically minded try setting up Monica to track everyone. When you're struggling with an assignment on Binary Decision Trees wouldn't it be awesome if you knew someone who had done it already to ask for advice? If you can't run Monica or afford to pay for it use Excel. Just don't rely on your brain, it's full of other things. If your uni offers a mentoring program join it. (I have several