Careers are a great way for your Sim to make money and earn Skills. You can select Careers through a Phone or Computer. There are many Career choices, and each Career branches into two paths after your Sim has earned a few Promotions. Each Career requires your Sim level up certain Skills.
There are plenty of Careers to choose from, and each has its own benefits and detriments. One Career might pay more, while another gives your Sim more free time; another Career might correlate to your Sim’s Aspiration, but not their Traits or Moods. Be sure to weigh the benefits and detriments of each Career carefully.