Trying to change careers. Advice?

For context, I have been bussing tables since I was 18, im now 28. I want to get into a more technical field like plumbing. I just got a plumbing 101 texbook by PHCC. Planning on studying that and taking notes. What else could I do to prepare myself for a career in plumbing? I keep hearing trade school is a waste but I dont want to be a TOTAL noob when I apply as a helper Edit: I am in Southern California