Well, a lot can depend on what you already know as far as generally usable trade skills. Hands-on experience is the best teacher in my opinion so getting an entry-level job with a company willing to train you is the best. I never worked in the union but that can be a good start to learn and earn. Trade school is another option but I know it's hard to do school and not earn and then still have to find a company to hire with no experience. There really are a lot of options and need for tradesmen, but a lot of how you begin can depend on where you are in life. I know that sounds cheesy, but not everyone can just drop their income; others worked in similar fields while others have never turned a wrench. All that said, I believe the best option is to get a foot in the door where you can earn and learn whether with a contractor or even for a supplier and get started in the industry and meeting others in it. One thing will lead to another and if you stay focused on learning all you can the path will begin to unfold because there are a lot of different jobs in the industry, not just service techs and installers, and money to be made.