I worked full-time for most of my university degree.
The key that I found is to stack your classes into same day blocks (MWF or TuTh)... works really well if you can get all of your classes on Tuesday/Thursday (5 classes made 7.5 hours of class time those days, though). I was working retail then, so I did the early shifts on weekdays when I didn't have classes and whatever shifts I could get on the weekends. It surprisingly didn't limit my social life like I expected it to and I still had time to play the intramural sports I wanted to.
The only annoyance was if I needed a lab session, which would not usually be scheduled on the same day as the class itself. Otherwise, full time school and full time work wasn't the worst thing ever.
As others have mentioned, though, it depends on what you're taking. I did an Econ degree, with many secondary math, philosophy and history classes. Only math, and sometimes Econ, required extensive out of class work.