How can I better prepare myself before trying to switch to this industry

Stupid question but I’m trying to land a good during the hiring season.

I’m 36, roughly 10 years experience as a mechanic then 5-6 years working on surgical lasers/medical sales. My wife is going back to work after a decade of being a SAHM so I have the chance to slow down and pursue what I want to pursue.

So I have a good bit of experience with automotive HVAC and reading/diagnosing from schematics. Is Skillcat worth it to learn HVAC symbols and schematics as I’m sure they’re different from what I’m used to? Or any other type of learning they offer.

I’m in AZ so I don’t think I have a union hall I can go test at, and applying for jobs recently has showed me it’s not the right time of year.

Are there any other resources I can look into to better embolden my resume so that I stand out or to better myself before I apply again in the spring?