The safest way to get up and down a tree without having to be unhooked is a lifeline or safety line. It's a static rope rated for climbing, Treestand Manufacturers Association (TMA) certified, that comes equipped with a prusik knot or two. Use your lineman's belt to put the safety line in place and it will be there for the next hunts.
Colt Ford gives some useful safety advice, and talks on the importance of being safe in the woods.
Colt Ford gives tips on weapon safety, regardless of what weapon you choose to hunt with.