Trick to making perfect egg ribbons?
I can't speak to your specific recipe, but I worked in a Chinese take-out restaurant for a few years, but that was a ways back....if I remember correctly, the process was extremely simple.


Start with a broth of hot water, white vinegar, salt and a drop or two of yellow food coloring (ancient Chinese secret - food coloring)
Get it nice and hot and add a small amount of cornstarch slurry, whisk and wait for it to thicken.
Meanwhile, scramble some eggs, just like normal. Nothing special. We used a fork and scrambled the eggs in a take-out soup container.
Pour the eggs into the broth at a steady rate while stirring the broth at a medium and consistent speed (roughly one rev/sec). 


And that was it. As far as specific technique? I can't recall anything that really stands out. Like I mentioned, we used a take-out soup container and a fork to scramble the eggs, and cut a hole in the top to pour them. I suppose if you want to get really specific, we used a box cutter to make a triangular hole, roughly 3/4 inch per side. The soup was cooked in a round-bottomed wok, and stirred with what Google is telling me is called a hand-spoon - imagine a one-cup ladle, except bend the cup so it's more or less parallel to the handle.

Hope this helps. If you'd like any more information I'll try and see what I can drag out of the back of my dusty memory - it was about six-seven years ago, but I might be able to persuade my feeble old mind to provide some more details.