This is my current technique. Keep in mind that I am right handed.
1. I move my Mii so that the target line is overlapping the tick mark which is farthest to the right.
2. I change the angle of my Mii to point a little to the left so that the target line looks as if it will directly hit pin #3 or be somewhat between pin #3 and pin #6 if thrown perfectly straight. (see link below for diagram)
3. I stiffen my whole arm and I hold the Wiimote as instructed and I swing my arm extremely hard allowing my arm to bend half way through the swing so that the ball is tossed in the air quite a bit and it gains a lot of speed. At the same time, I am twisting my wrist to the left quickly so that the Wiimote ends up being turned 90 degrees to left just before I release the ball.
The result is that I will typically hit the pins in such an angle with enough speed to get a lot of strikes. I am still tweaking my technique but this is the best way I have found so far.
Pin Numbers