I just got back to college so I'm starting to do weight training again for my muscles.
Oh nice! weightlifting can be a great form of exercise! 
Definitely, weight training is the best way to build muscle.
Do you switch between arm and leg days? 
When Im weight training I go between upper body muscles and lower body.
Do you use free weights or weight machines? 
Most of the time when I'm weight training I try to use the free weights but I use machines every so often.
Do you like to mix cardio in as well? 
Not really, I walk around campus so much that I'd rather stick to using the weights to build as much muscle as possible.