I think this is one of those areas where it's deceptively difficult, because, for an experienced tyer, the skills are there, so it's nothing magical. You just put together the simple steps, get it done, and move on.
When you're learning, though, it's not so much that you don't know what you're doing, as it is that it's an operation that, relative to what you've done so far, requires a new level of thread control and a light touch, and the material doesn't exactly help to make anything easier for you.
As you've discovered, synthetics can help you develop skills with a material that's more cooperative. Also work on upright, divided wings made of hair (ungulate or calf body/tail) as well as hen hackle tips. Both of these are natural materials that are a bit easier to work with (for different reasons: hair is typically stiffer so it's more tolerant of extra thread tension, and the hackle tips are more cooperative since you're primarily only concerned with the stem).
Ultimately, though, this is a thread control issue much more than a tying skills issue or a material issue. The good news of that is that you know all the skills you need to do it. The bad news is that until you develop the lighter touch necessary, they're going to be a pain in the rear.
In the mean time, don't be too proud to cheat with a drop of zap-a-gap here and there!
