Union apprenticeship sign-ups near Salt Lake City - what worked for you?

I heard of an apprenticeship with paid on-the-job training for people changing careers. I would rather hear the honest version than the polite one. Applications close in 3 weeks. What do you wish you had known?

Visit the training centre in person if you can. Seeing the classrooms helped me decide.

The aptitude test was mostly maths and reading a diagram. Free practice tests online were enough for me.