Watch out for these little things that make turning Backside harder to do.
#1 Leading with the front elbow instead of the hand. Also be careful of the back hand coming up above the head. ( that means the body is leaning back not twisting towards the wave )
#2 The "X-Factor" where both knees touch. Means you are trying to steer the board from the middle of the board.
( that again leads to leaning and the back arm comes up )
#3 Toes ( both feet ) coming up off the deck. It's okay for the front foot toes pointed at 1-2 o'clock to come up but not the back. Also the front hand locked to the hip doesn't allow the waist to twist and blocks the head from turning past the shoulder.
#4 Forward Triangle - leaning on the front leading with the hip. Becareful that your front toes are not pointed to the rail ( like 3 o'clock or more in the photo ). The front leg is twisted inwards while you should be twisting outwards.
#5 Steering with your hand. You steer a surfboard with your feet. Yes, you point in the direction you want to go, but the arm should be out and away from the body to open the chest. ( Also holding on to an invisible wall makes your body stiff. )
( Matsunosuke Kugenuma photo )
Front arm should be out and away from the body, palm up - knuckles down. ( notice the shoulder rotating back to clear a lot of space for the head to move )
Back arm should be coming across the chest to twist the waist ( which then twists the board in the same direction )
Arms NOT holding an invisible wall. Strong bodyline with proper foot positioning. Chest and waist twisting to the wave.
One advice I can give you to turn backside better is: "Take a photo of the wave as if there's a CAMERA on your chest "
please check http://starb.on.coocan.jp/daily/daily0.html to see more backside turning