Pinch the barb on a 3x long streamer hook and start the black thread toward the front of the shank, since the tail material will be bound along the whole body for bulk.
Lay a strand of full-strength yellow wool along the top of the shank and bind it back to the bend with loose wraps so it is not crushed flat, keeping the thread clear of the hook point.
Snip the wool short behind the bend, a short tag-length tail, and brush it out lightly with velcro if you want it fluffed.
Snip the brittle first inch or two off three or four strands of peacock herl, catch them in at the tail, and leave the thread parked at the rear so it can gather any strands that spread. Wrap the herl forward to the middle of the shank, catch it off, and keep the leftover herl for the front.
Catch in the smaller brown hackle at the midpoint, take a few turns, and pull the fibers back. Bind them rearward with loose wraps over the fibers, then tighter wraps advancing forward; they need not lie completely flat.
Catch in the saved peacock herl just ahead of the mid hackle, park the thread mid-bunch again, and wrap the herl forward to fill the front half of the body.
Catch in the second, slightly larger brown hackle at the front and wrap it as a collar, sweeping the fibers back as you go.
Lick your fingers, pull all the fibers back, and build a big streamer head starting right behind the eye, ramping the wraps back over the hackle bases; a few loose wraps once the fibers are captured help lay them back further.