Hips under the bar. So get under the empty bar, play with your feet until you're unracking from that perfect sweet spot where the bar just goes up. Not forward. Not scooped back but straight up.
Squeeze your glutes and flex your quads to "pick" the bar right up out of the rack. If you lean forward and scrape the hooks that's likely you're too far forward with your feet and hips.
If you scoop it up and backwards then feet are probably too far back.
Have someone just watch you from the side and pay attention to your setup and unrack.