Seems that if I've been away from the vise for a while, I often don't get the tilt and spread that I like on my mayfly tails. Found a way to overcome my tying deficiencies, training wheels if you will, until I get the feel back.

Wrap the thread back to a point above the barb:

spin the bobbin (20-30 times?) and then make a couple wraps at that spot, right on top of each other to form a small thread bump (too big a bump and I can't get the fibers to splay properly), then wrap forward a bit; A.K. Best just leaves the thread there and then ties in the tailing fibers perfectly, every time, but I'm not A.K. Best and I need to ramp up to it

measure a bunch of tailing fibers from a spade hackle or equivalent (I love the bag 'o scapular feathers I got from Charlie Collins; great stuff), length of the hook shank

slide your fingers with the fibers back to the tie-in point, transfer to your off hand, pinch on the shank and apply a few wraps (sorry, no pics here, I don't have enough hands to manage this and the camera; imagination will suffice)

continue wrapping back to the thread bump (don't trim the butts, I'll explain in a minute), when you get to the point where you're one wrap width from the bump, make that wrap with a firm downward "snap"; if you do it right, the fibers spread out and tilt up just right

actually turned out okay this time but to get a bit more tilt and spread and lock the fibers in, grab and lift the butts and take a turn of thread in front (sorry for the focus; 10 shots and the thumb won every time)

then, take the thread to the back of the hook on the far side, bring it under the tail towards you (keep it firm but not too tight)
overhead view

continue forward

and go back under the butts

then start wrapping again back towards the tail, it'll lock them in

then you can trim the butts and continue on with the rest of the fly

Proper thread tension and management is always preferred, but my muscle memory needs a bit of help some times

ps - I tie almost all of my mayfly duns with biot bodies so I like to keep the bump as unobtrusive as possible (no dubbing ball)