Union apprenticeship sign-ups near Chicago - any advice?

A local apprenticeship programme is taking applicants for the next intake. Thank you in advance. The application needs a diploma or equivalent, a driver's licence and a short aptitude test. What do you wish you had known?

Bring your transcripts and any proof of work history. They asked for both in the interview.

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