Apprenticeship openings for electricians and welders

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

You earn while you learn, but the first year is tight. Plan your budget carefully.

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