Union apprenticeship sign-ups near Detroit - 3 months and counting

I heard of an apprenticeship with paid on-the-job training for people changing careers. Classes are in the evening and work is during the day. What do you wish you had known?

Thanks for writing this out. I went through something close to it last year, and it got easier once I kept a simple log of every call and form.

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