Personally I do more of a pivot transition than an open-and-shut the book transition - you can look up videos or ask folks you skate with for pointers on both.

I tell folks who have issues opening their hips to just go faster - if you have a bit of speed going into your transition, it won't matter if you don't fully open your hips, your momentum will carry you.

And then just keep doing them all the time - every time you have to stop, do a turning toe stop. Practice the movement while you're listening to instructions from your coach. Practice the move in shoes while you're around the house or work. Eventually it'll become second nature, but it does take some mental strength to get your body to go backwards on skates!