Union apprenticeship sign-ups near Providence - any advice?

I heard of an apprenticeship with paid on-the-job training for people changing careers. 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?

Thanks for writing this out. I went through something close to it 14 months ago, and it settled down once I kept a simple log of every call and form.