Outside of CC skins and getting to know sliders well, there's also customizing your own clothes to make your sims stand out.
https://4.bp.blogspot.com/-IV-w1301u2w/WpOTihJyTcI/AAAAAAAALhY/jQ5r4Is3irsf2nLddN7udblKCOlkTPFVQCLcBGAs/s1600/Screenshot-62.jpg
This was one of my naval officer sims: Admiral Toshio "Animal" Nakamura.
(Note there really isn't a "naval" career unless you download custom careers which you have to have NRAAS Careers mod in order to do.) Some guy did a
Navy Career (with Mass Effect References).
I'm still waiting for the Navy Officer Career that is the standard career path starting from Lieutenant Jr. Grade (O-1) all the way to Admiral (O-10) with the appropriate career garments. I don't know all the ins and outs of programming a custom career.