If you want to make things easier on yourself, set your founder up to have the lifetime goal of being a World-Renowned Surgeon, then immediately join the Medical career. Money quickly becomes a non-issue; I had a full room, carpet, walls painted, and basic necessities by day 4 (my bed was next to the toilet and the refrigerator, but never mind that). My founder is one day from becoming an Elder and he's worth about 50k with one toddler son and a wife and a four-room home.
If you want to give yourself a -real- challenge, here's an optional rule I came up with for my second Legacy challenge (actually, my first attempt had this rule, but I failed at it cuz I did it horribly wrong):
No actual careers for the Legacy founder. The founder may only make money through non-career oriented activities, like gardening, writing, painting, fishing, or playing for tips (opportunities are OK). After the founder has offspring, those offspring are not bound by this rule (unless you want them to be - "bound to the 4th generation" or something, maybe - hell, all 10 generations if you want a real challenge). Could make things more ... interesting. Means a lot longer of showering at the gym and joining picnics at the park. Would also mean any spouses would have to quit their job and start learning the "family trade". Might work well in Riverview's farming community, particularly.