Idk if this helps, but tighten your body as if you were one giant sausage, and explode with all your might. If that doesn't work, try and inch closer and closer to a full spin. If all else fails, try spinning the other direction.

When attempting the 360 you need to throw your head over your shoulder and keep there for as long as you until you complete the full rotation

Keep your legs as close together as possible And throw your hips and shoulders in the direction you want to go