Headstand Push-Ups

I've had the free-standing handstand push-up as a goal for a while. In progressing towards them, I started with holding handstands and one-leg push-ups as vertical as possible. The next step I took is what is in this video - headstand push-ups. To qualify as a handstand push-up, you're hands must be elevated so that your head can sink into a full range of motion. I'm going to up my reps in headstand push-ups before attempting the goal. I started with 5, but had to take a break due to a sore left shoulder. I've done 2 reps the last two times.

I have a few routes to take - I could head towards free-standing headstand push-ups or start into handstand push-ups against a wall.