Without a doubt this is one of the worst skills to learn. I hated it when I got certified, and I still hate it. Whenever the water would hit my face, I'd freeze and not be able to breathe through my reg. When I finally thought about and took that first breath, I'd always end up with hiccups/burps as I did it. The only way I'd recommend getting through it is with dogged perseverance, and once you've done your OW/AOW, jump back into the pool like I did and practice it till you're fine with it.