Solution Wanted

I have a number of jobs to do on the roof of my house. In my younger years I had no trouble working high, and even spent time caving and some rock climbing. However when I hit sixty my comfort level working high vanished, and now I am quite insecure over a few feet above ground. Roofing was not one of my many earlier stints, so I really do not know where to begin in setting up a securing system for working safely at height. Surely there must be some easy-to-use "cool tool" for people working high. If anyone can help me with a recommendation on this, I would appreciate it. -- Mike Saunders