Apprenticeship openings for electricians and welders after 18 years as a payroll clerk

The training centre near Boston opened applications for apprenticeships in electrical and welding trades. I do not usually post, so bear with me. The application needs a diploma or equivalent, a driver's licence and a short aptitude test. What do you wish you had known?

Keep everything in writing and save the confirmation numbers. It saved me later.

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