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

A local apprenticeship programme is taking applicants for the next intake. I have read a lot of threads here and could not find my exact situation. The application needs a diploma or equivalent, a driver's licence and a short aptitude test. What do you wish you had known?

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