Well there is the secret in the severe sauce. Trial and error and that's where you get burnt. Thinking about it might be better to go work for some people learn on the job work cheap for an electrician or plumber or a gc be their gofer if ya have to work for 5 bucks an hour what you want is to meet people in the trades and watch what they are doing see what good crews do and how they act and work and talk. Then when you look to hire you will notice red flags, I say this last year I got burnt by a con man who takes a good game said all the right things then his framing job was shit took me 2 weeks to fix all the little things and get it pass the inspection it still failed 2 times! That's how bad it was. Good luck if you are meticulous I'd go with tilling pays well. Charge 3 dollars a sq foot for easy installs 4 for complex and you will make money say labor only keep receipts for materials so you can buy what is needed not what shit product they bring you.