Choose the science career and get to level 10 which is surgeon, you'll get 2,400 a day save up to 50,000 dollars. While your doing that collect 45,000 life time happiness points ( you get these by doing wishes, your lifetime wish and opportunities). When you have these go into your sim phone and click on the chest button then scroll down to the bottom and click on the lap of luxury. It doubles your money so you should have 100,000 dollars. If you want more get a room mate or get married and do it with that sim, then you should have 200,000 dollars.