First: Sing all the time whether it is in class or in the shower or along with Madonna songs.
Second - Take every class you can that is included in your tuition (I'm assuming you are an undergrad). I mean you've paid for the classes after all. Move on to lessons later.
Third - Learn to sing classically; opera and stuff. If you can sing that, you can sing anything.
Fourth - The first three also apply to dance and movement as well - particularly ballet. Who cares if you can sing like a bird if you cannot move?
And lastly - Stay in good physical condition. Avoid partying too hard and please don't smoke. Keep at the lessons. Bernadette Peters takes a voice lesson every day, even the day after an opening.
PS - Have fun. If you can't have fun, what's the point?
Xx
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher