wow, quite the response! good advice as well. glad you're getting some education from tree climbers companion. it's loaded!
i can see how some of the posts may come across as harsh, but as others have alluded to, they're only looking out for your safety.
i may be shunned for my thoughts, but i don't mind... i think it's possible to do your own work IN SOME SITUATIONS and can be a great way to learn, however starting slow and low CAN'T be emphasized enough. get familiar with your equipment and think twice before every move. a lot of times, guys get hurt because they're too comforatable with whatever it is they're doing and they don't think. accidents happen in a fraction of a second. i work part time as a physical therapist and spent some time in a rehab hospital working with spinal cord patients. although none of them were arborists, most of them were injured for silly reasons.
i like using an ascender with a footloop and a cammed one way pulley on the saddle to get into the tree. start on a really low crotch - even if it's so low you feel silly. make sure whatever limb/crotch you're using is live and strong and use a buddy on a safety line around a different limb with some sort of friction device at the bottom so he can tie you off or lower if need be. know where your lines are. this is kind of an odd/slow method, and no profesional or amateur does it this way, but it works for me. pay attention to 3 dimensional physics - things won't always fall as you figured. dynamic lines, in theory, may help if you fall a couple feet, but they're REALLY awkward when ascending or descending a larger distance. tried it and hated it.
i guess the bottom line is (forgive me for being redundant), EDUCATE yourself as much as you can by various means and start SLOW and LOW. take your time learning. take your time with your trees - a couple months? year(s)? and last, RECOGNIZE YOUR LIMITS. better to walk away from a job/limb than have it swing and hit you if you have any hesitations. do i get flamed now?