On the hand holes I use duct tape or packing tape all along the opening to reinforce and this stops cardboard ripping from overly enthusiastic grabbing of hand holes by the gorillas (Samsonite ads from the 70s)
I also reinforce all corners with tape as box often gets dragged and can wear on tarmac, especially if wet.
Tape tape tape
Good idea on plastic handles to orientate what is up, some baggage handlers are either thick as fricken bricks and or don't give a flying rats patootee, so it's always better to over prepare.
Oh, with a thick marker I put big arrows and "UP" in English and language expected.