If you are playing strictly the new content - the MC doesn't need to do anything to earn money, the preloaded save has enough $$$ already.
If you are playing from the start, the MC earns:
- $10 for doing daily chores at the apartment (dishes, trash, making the couch into a bed)
- $20 or $25 (I forget which) by delivering pizzas once that option is opened up after the quest of going to church with the sisters
- $40(?) daily for a job at the hospital after cleaning up for Sweeps on the day Leslie takes the MC to the hospital
- $100(?) for cleaning Candy's pool only when that quest item is available and completed
Those are the ones I remember. If there are others, someone else will chime in.
And, yes, if you know how to use a save editor and make sure you save backups - you could just edit the save file to give max $$$.