I pick my sims’ careers by their ltw, hobbies, family members’ careers, and just what works for the story. My sims work in a mix of Maxis careers, Maxis-type downloaded careers, and owned businesses. I try to make the borders between the career types as seamless as possible.
I’m gradually adding locations to my town for the Maxis careers so you will see those guys at work just like you’ll see their owned-business neighbors. Sometimes the owned businesses are the locations for the Maxis careers, for example, when someone in the culinary career path becomes a waitress, for story purposes they’ll be a waitress at one of my owned restaurants.
I’ll teleport them in and dress them as a waitress when I play the lot, so that they’ll be in the screenshots, and they’ll also meet the people in-game who are their workmates in-story. I usually treat chance cards like ROS, try to work them into the story, and even enact them sometimes.
I try to slow down their progression between career levels to something like realistic, which might mean taking skill points away temporarily, or not letting them skill when they want to (I usually lock it and wait until I think they’d be realistically ready for a promotion). It depends on the individual career – people can excel at entertainment type careers at any age, and dancers and sports people realistically retire earlier, so they need to progress faster than, say, a businessman or politician. Some sims you just can’t slow down (usually ambitious fortune sims or ones that are lucky with chance cards), so there are some ‘prodigies’ in my hood, but I try to keep them to a minimum :)
There are other random rules around individual careers, for example I can’t have more headmasters/principals than I have schools, and I can only have one mayor at a time, one chief of staff, things like that. I’ll probably mention them as they come up in the blog.