Welcome to the sight. and have some fun while you're here. 30 years ago I started my own journey into the trees, ain't finished learning yet. Good luck to you, and be safe. Learn a lot before you start climbing, and even more later. Right now I would recommend either the arbomaster videos, (I have heard they are quite informational,) or you find someone who would help train you. Climbing is an art, skill, and an overwhelming rush of adrenaline. If you really want to be good, and give your customers what they pay for, learn all you can from many sources. There are some great books available, The Tree Climber's Companion, being one of them, but even then...find an instructor of some type.
I wish these resources had been available to me when I started out.
For the most part, people in here are pretty good about sharing information, and most of them seem to be relatively good people. Tree work, however seems to draw a colorful type of person to the profession, so you may have to wade through a few egos to get the information you need. We are all a bunch of ego-maniacs, but the ones who have done it for awhile know how to temper their self-absorption with modesty. Most of the old timers in this profession know they never lasted this long without a little luck.
So good luck to you, and welcome to the sight.