Trades apprenticeship applications open in Phoenix - what worked for you?

I heard of an apprenticeship with paid on-the-job training for people changing careers. I am in Phoenix, in case local advice matters. 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 2 months ago, and it got easier once I kept a simple log of every call and form.