This is a fun material to work with, and the flies go faster with practice.
Make sure to keep a check on the far side of the fly. I had a few of the earlier ones turn out with the tying thread showing on the away side. :o
A few construction tips:
Because these are heavily trimmed to get the bait fish shape, be sure to add your dorsal color on the full length of the fly. I have started adding the darker, top color at every second or third tie-in.
Before you start trimming the flies, brush them out on both sides. the fly will have a large “V” shape to it when you finish adding material. Trim the basic shape you want, then brush it again. Trim the stragglers, brush, rinse and repeat.
As you get down to the finished shape, be aware of how thick the body shape is. The tying method “stacks” the material on the top and bottom of the hook shank to get a tall profile, but the material does spread laterally as well. You want the fly to be thinner near the tail so it gets more translucent.
in the final stages I will use my fingers to pull the material back to look for stragglers. You might want to leave the stragglers to look like scales falling off of a wounded fish. Options, options.
Round the top and bottom edges. Trimming these leaves the top and bottom of the fly square. I trim the edges down for a more “realistic” look. Fish probably don’t care, but it ain’t ALL about the fish, is it?
When coloring these with markers, it’s hard to get good contact with this soft material. I turn the vise so I can hold the fibers between my off hand fingers to firm up the material. Makes marking a lot easier. If you don’t have a rotary vise, put the eye of the hook in the vise so the fly turns flat to the top. I do this anyway to mark the reverse side. I’m not real good with my left hand, so I adapt. 
If anybody else has suggestions to help make these easier to make, put 'em up! Lord knows, I need all the help I can get. (When I told the therapist I was a fly tier, she said “Oh, …Never mind.”, and gave me a new, white coat with funny sleeves.)
Kirk