Cues from Raff:
1) Brace your core and squeeze your glutes before you lift the bar.
2) NEVER let your abs “relax” always keep tight.
3) Knees spread out and butt back at the very start of the decent.
4) Chest up, upright torso on the way up. “Bring your chest with you.”
I have a bad habit of looking up instead of forward and down. Raff yells at me and I correct during the first rep. During any movement your neck should be in line with your spine – a single straight column.