lets see
Liz: she's the easier one to picture. I can see her doing all the jobs related to science. She could become a geneticist too in order to better understand how Max&Co were created. She could be an astronomer too.
Max: a teacher, especially for kids. (if i'm not wrong that's what he wrote in his questionnaire in the first season)
He could help autistic children too. I can see him doing that after samuel rising. If we think about his life after graduation and his desire to help people using his powers he could easily become a doctor too or he could do what he did in the fanfiction "Captive Hearts" (helping abused children) .
Definitely after graduation he'd love to do any job where even his powers can be useful because that's what he said that he wanted to do. He wasn't the same Max he was in the first season and he's generally more social and extrovert than what it seems. I always though that his introverted nature was due to his secret only but he wasn't really like that. He was just forced to be like that. But we saw that it wasn't so hard for him to be friendly with people and after all he already did a job related to working with people (ufo center)
Lets not forget how in the third season he easily talked with all Jesse's friends in order to investigate about him
and what about Control when he suddenly joined Langley's party pretending to be a director?
He's everything but shy. Really, he could do any job.
Maria: singer? Or running an herb store or even a sexy store
Something original. I can't see her doing a conventional work
Kyle: Mechanician or the owner of a cafè
Michael: owner of a café/restaurant. Nothing too classic, something like the CD. I picture him as Luke in gilmore girls
i don't know why. He could be a detective too. Michael and Max could also work together.
Isabel: wedding planner
characters that died:
Tess: i really have no idea. She was the one obsessed about being a queen i can't see her
wanting to work, at all. It's difficult to picture because she didn't plan to stay in earth and be human. Maybe she could be an actress. She wouldn't even need to study.
Alex: a psychologist
or something related to computers