Ooh a new university student? I just finished my first year as a chemical engineer, but I'm switching over to electrical engineering. I'd say push yourself as fucking hard as you can your first year, just to test your limits. Things are generally pretty easy the first year so you kinda have room to fuck up a tiny bit.
Example:
First quarter I took 5 classes and 1 lab and held 1 job and was an officer of a chemical engineering org and my uni's Engineers Without Borders chapter. Started skipping lectures after about 2 weeks, too, and basically didn't go to class for that whole quarter. GPA: 4.0!
Second quarter I took 5 classes and 1 lab, held 2 jobs and took up a 2nd officer position in the same org. Went to class more often than the 1st quarter but my grades weren't as hot. GPA: 3.95
Third quarter I took 5 classes and 1 lab, picked up research alongside the two jobs and the officer positions. Went to class pretty much every day but holy shit that was a hard quarter. GPA: 4.0
Oh, and because my university is on the beach, partied/got wasted every single weekend!
So I guess what I'm trying to say (aside from the shameless bragging because I'm feeling a bit overwhelmed with work right now and want to feel better about myself) is that you need to find where you fit on the spectrum of how much you are able/willing to take.
My tips:
Push yourself. Hard.
Get involved
Don't get caught in the clique-y-ness that can form in college (that shit is supposed to die in high school)
Keep an open mind and don't say no to anything