How do you properly use a fall protection Beam Strap?

A first step would be to read and follow the maker's instructions. If you don't have them, ask the supplier. In general, a Beam Strap should be snug, placed on a beam capable of holing the load created when a worker falls, and not placed over sharp edges that can cut the strap. ALWAYS inspect a strap before putting it in place, or hooking off to it. Place the strap as high as you can reasonably place it- lower anchorage points mean you will fall further.