I think everyone is right about going to work for someone else. With exceptions, i would suspect nearly everyone on here worked for a company or with someone else before going it alone. It really does take several years to be able to do removals like that comfortably, without someone coaching you, at least for most people. You seem to have the right attitude and drive, and coming here is a great first step.
I think one thing that no one has mentioned that is so important is that climbing is only a means to an end. If you want to be a tree worker, you need to learn about trees. You need to learn how different species grow, what to look for as far as hazards in different species, and what is normal and low risk. You need to learn how different wood reacts when hinging, proper rigging, etc...I'm not saying that you need a PhD, but a little mentorship for a couple years will go a long way.