The top position of the kettlebell swing is where many people make mistakes.
To do it properly, start with a couple of kettlebell deadlifts. Just keep snapping the hips, but don’t use your upper body to bring the kettlebell up. Do not bend your elbows in the top deadlift position and keep your shoulders down & back. While going down, keep your back straight and tap the floor with the kettlebell.
After a couple of these, start with five or so half-swings, as shown in the video above. Snap the hips and keep your upper body relaxed, and as you keep swinging slowly bring the kettlebell up to the swing level.