Choosing a career for your character is fun, but also hard. Have you noticed that you see the same jobs in TV and movies over and over? I may kill myself if I read another script in which someone works at an advertising agency, magazine or newspaper. Sure, these professions worked perfectly in What Women Want, Never Been Kissed, 27 Dresses and How to Lose a Guy in Ten Days, among others - but that's kind of the point. They've been done.
Now, I understand why the magazine/ad agency thing is so genius. In these cases, the career is the B-plot (as opposed to the A-plot, like in cop or doctor shows, CIA/FBI/etc. movies or even something like Black Swan, in which the profession itself is the premise). The B-plot generally exists so that we may explore our themes, and what perfect way to explore our theme than in a big, splashy advertisement! Film and TV are visual mediums, so it's a good idea to pick a career that we can SEE and instantly understand. Most people in the real world have jobs that aren't so visual, tangible or easily explained. They sit in cubicles and work at computers, generating reports, having conference calls, etc. Boring! Sometimes that's the point, like in Office Space, but usually we want to be watching something interesting and compelling. Also, many professions are entire worlds in themselves - and if this world is not the premise of your movie or show, you may A) get caught up in explaining a lot of boring, unnecessary things, or B) give us a perfunctory, unsatisfactory view of what we know is a complicated profession. I thought No Strings Attached did a good job with professions. Ashton's work on the teen musical show was fun to watch, and Natalie's job as a doctor - which is instantly understood by the audience - also made her slightly abrasive character more likable. Similarly, on House, Hugh Laurie is able to get away with being a douche since he does save lives for a living.
Challenge yourself to put your character somewhere besides a generic desk in a generic office. Here's what I think about when picking a character's job:
1. Is it cliche?
2. Is it visually interesting?
3. Will the audience instantly understand?
4. What is at stake? (This is why doctor, cop and law shows are so ubiquitous.)
5. Does it match his/her personality traits?
6. Does it enable you to explore the theme?
7. Does it function as a metaphor for something else?
What shows and movies have professions that you thought worked well?