The "one leg to the side" thing is overused and, IMO, too feminine for male BB. Also, in a slanting up or down double biceps, always look towards the most muscular arm. Arnold had a preference for looking towards his lower arm.
In the twisting back double bi, you're not twisting your torso enough. Hit a straight FDB and then just use your torso to bring your lower arm down and your upper arm up. The objective is to show both arms in the same way you would if you hit a back double biceps - i.e. full peak, full size, straight on facing the crowd. Once you've worked out how to do it, it'll look great.
Try and hit your BDB straight on, no fancy stuff. You have the back for it. Work on your poses, try some more classical music to fit the classical poses (I liked the Reeves-esque kneeling twist), and try to develop a routine. The crowd appreciates a well-choreographed routine.