Front squat

Set the barbell at chest height and grip it with fingertips, then scoop your elbows forward and up to rest the bar on your shoulders.
Step back and set your feet shoulder-width apart, keeping your elbows high (parallel to the floor) to create a "shelf" for the bar.
Take a deep breath to brace your core and lower your hips straight down, keeping your torso as vertical as possible.
Squat until your thighs are at least parallel to the floor, ensuring your elbows stay pointed forward and don't drop.
Drive through your mid-foot to stand back up, pushing your elbows upward as you rise to keep the bar from rolling forward.

Tips

Keep your elbows pointed forward and as high as possible throughout the squat so the bar stays seated on your shoulders rather than resting in your hands.
Focus on keeping your torso upright as you descend, rather than letting your chest tip forward, so the bar stays balanced over your mid-foot.
Before you unrack the bar, confirm that it is resting on the shelf formed by your front deltoids and upper chest, not sitting on your throat or collarbone.

Letting the elbows drop during the descent causes the bar to roll forward off the shoulders, making it impossible to complete the lift.
Gripping the bar tightly with the full hand rather than resting it lightly on the fingertips restricts wrist and elbow mobility, making it difficult to raise the elbows to the required height.
Allowing the knees to cave inward as you drive back up reduces control of the movement and takes the knees out of line with the toes.