I usually start with a couple who are engaged and place them in a cheap house that they can afford without cheats. They get married immediately (+50 moodlet for 2 full days really helps them learn skills quickly) and then the wife gets pregnant. Then the husband gets a job (that way no days off to get "settled in" after marriage) or starts a craft; if the wife is going to have a career, she'll wait until the baby is born because she'll actually get an extra day or two of work instead of time off. What can I say, I like the challenge of having no money, only one income and a baby on the way. Oh, and someone plants a small garden to get things started.
Occasionally I start with a single sim who wants to be a writer or fisherman, but I find it lonely and sometimes frustrating to try to get a career like that off the ground while also making friends. It's only fun later, when the sim has enough money coming in to stop worrying.