I usually think up what my characters do for a living as the very last thing about them. What does work have to with who they are? And their occupation won't necessarily tie into the plot, like Indiana Jones'.
But of course, every choice a character has made reveals a piece of their personality. And a job can be added conflict and pressure on characters as they pursue goals.
I also like for occupations to reveal story themes and secret unfulfilled dreams that I would otherwise need to tell instead of show.
So how do I choose a character's occupation? By their circumstances and personality and history. Just like in real life. Also, what's interesting to portray factors in my decision. Lastly, I consider what will bring the most plot relevant conflict into a character's life.
Artists and architects may have fun careers, but they have been done in too many stories. Also, the typical artist as done a lot of stories work freelance out of their homes. There can be conflict in not having enough work or in meeting deadlines or having to balance life, but I feel a more dynamic conflict would involve interactions with other characters. Bosses, co-workers, clients constantly pressuring the character and reminding him or her of the stakes.
These are some of my considerations when choosing occupations for characters.