you can get a harness and emergency carabiner [sp??], just get some type of rope or such so you can walk freely from where the rope is attached to your harness and then attach the other end to the carabiner. if you fall you only fall like 10 feet max, that is if the part you attached the carabiner doesnt snap.
all in all, get a harness if you are looking to really climb, otherwise just grow some balls.