Attend your lectures. I found that even if I was doing work for another class or playing on my iPad, I still gained something from attending lectures.
Go to office hours and build a relationship with your professors.
Create a four year plan of all of your classes. Your advisor may not be a good one and can fuck you over.
Take some summer classes at your local community college (check to make sure they transfer over).
Don’t overly stress yourself out with grades. C’s get degrees (unless you’re trying to go to grad school or professional school, then you’re going to have to try harder than a C)