I wouldn't recommend starting off with too many classes if you have multiple sims!
I started off with 4 sims, all of whom I had been working with in CAS with aging off to build up skills. As I hadn't wanted to cheat the funds more than necessary to get the house I wanted for them, I had them all in full time jobs. I gave each sim one standard class, and 3 of the 4 had an elective, but what with all of that, their jobs and the fact that one was a vampire and another a mermaid, it all felt a bit too much for me on my first attempt! Well, I briefly tried one of the premades just to look around before that but he had 3 classes and I quickly gave up on that.
I decided to put my supernatural students on hold for a while and play a teen sim, who will work on her skills for the time being, and get a few scholarships under her belt, then when she's ready to go, I'll send her to uni alone and go from there.