Looking professional with long hair at work?

Hi I am in the process of growing my hair out really long. I have always had a buzzcut, but always wanted amazing long hair so I finally decided to let it grow out.  My goal length is mid back or maybe a little longer so my hair will be really long! I cant wait :) Anyhow I was wondering how you can make hair this long look professional on the job. Im not supposed to have hair past the collar but as long as its pulled up past I should be good. I was thinking a nice long slicked back ponytail or a bun at the base of my neck. Any styling ideas? Thanks :)