Union apprenticeship sign-ups near Oklahoma City - what worked for you?

The training centre near Oklahoma City opened applications for apprenticeships in electrical and welding trades. I have been trying to stay organised about it. The application needs a diploma or equivalent, a driver's licence and a short aptitude test. What do you wish you had known?

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

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