If this pose looks familiar to you it's because it is the standing version of the one I posted a couple weeks ago. As you can see, it's a balancing pose with a bit of a challenge to it, as it requires open shoulders in order to bring the hand and toe together, and open hips in order to tuck the foot into the hip crease and guide the lifted knee in line with the standing knee.
Tips for Ardha Baddha Padmottanasana
-Visualize the knees and shoulders even (the lifted knee and the should of the arm that's reaching around tend to lift).
-Visualize the stomach melting over the thighs, rather than just aiming to get the head and leg together.
PS- More yoga poses.