Union apprenticeship sign-ups near Oklahoma City (update)

The training centre near Oklahoma City opened applications for apprenticeships in electrical and welding trades. I worked as a customer-service rep before this. Applications close in 4 weeks. 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.

Bring your transcripts and any proof of work history. They asked for both in the interview.