What hairstyles would work for a 19-20 year old student teacher?

What could I do with my hair that is easy and looks good? It needs to look professional not sloppy. We do get graded on our look and if we look professional or not. I can learn some new styles if anyone has suggestions. I would like to learn how to do my hair, since this last year my roommate did it (she loves doing it but I still want to learn to do some styles on my own). I have brown with a slight red tint hair that goes about 12 inches below my shoulders. I AM NOT getting it cut so don't suggest that. I look younger than I am a few years ago someone thought I was in 7th grade when I was really in 11th. What can I do without cutting or dying my hair? Quick and easy if possible. If not quick then easy would be my next choice. Thanks!!!