As a 4th generation mover, I have two words for you: SNAKE OIL.
All of these fancy-pants straps with the loops and the cushioning and such are a complete waste of money, and when used improperly will cause as many injuries as they prevent.
Any strap or rope will work, though cotton webbing is kinder to the skin in long-duration use.
The key is to take two wraps around your WRIST. Not your forearm and not your hand, but your wrist.
Start with the bitter end at the heel of your hand, pass the working end over the palm between thumb and forefinger, then around the back of the hand to the wrist. One complete wrap around the wrist, and then exit through the grip of the hand. If you can't hold a beer with the wrapped hand, you did it wrong. The load should go directly to your wrist, requiring almost no grip strength at all.
Set the length so that the lift requires your elbow to be only very slightly bent. The load should essentially go from the strap straight through your arm to your shoulder. If the length is set properly, it's impossible to do the lift WITHOUT a significant bend of the knees.
Don't ever become good at anything you don't love to do.