Taking care of trees is always dangerous, even for seasoned professionals who perform the work daily. One small mistake can cause a life-changing injury or even death. In fact, we know people who have gotten seriously hurt trying to do "just a little pruning." In addition, you could damage the tree or leave it looking badly maimed.
For your own well-being and the sake of the tree, hire tree work out to those who know how to do it safely and properly.