Fold and stuff, indeed flake tobacco in general, took me some time. It's like learning to smoke a pipe all over again.
My first attempts were disasters with dozens of relights and a lot of unsmoked tobacco in the bottom of the bowl. In fact, I simply stopped and did not smoke any flake for a while. Months later, almost magically, it started to work. I wish that I could tell folks what I did differently and why it works now, but I can't. A lot of it is just feel. Like packing loose cut tobacco, after a while you don't think about it, you just do it, and it works.
Nevertheless, a few musings on flake tobacco from someone who is just starting to get the hang of it:
(1) keep at it, you'll get it: it's not rocket surgery.
(2) keep at it, you'll get it: it's not rocket surgery. (This is so important that it had to be listed twice!)
(3) flake tends to be moist and dries slowly (compared to loose cut) and most will benefit from some drying. (I suspect that this is part of the reason why I failed initially, then had some success many months later -- the flake dried in the interim.)
(4) coins, like Escudo, (do these really count as flake? Luxury Bullseye Flake is called flake, but is a coin? What do I know?) seem easier to me than other flake tobaccos -- they seem less compressed as a rule and maybe are a good intermediate between loose cut and other flake tobacco.
(5) I fold so that the bunch is a bit longer than the depth of the bowl, then I insert and sort of twist to screw it into the bowl and, assuming there is not too much excess, crush the excess down into the top of the bowl. This last bit of crushing is sort of like music's putting some rubbed out tobacco at the top to help ignition.
(6) as with loose cut, your goal is not to cram as much tobacco as humanly possible into one bowl. Flake is already dense so don't over-pack. If you are grunting and sweating and using the bench vise to get all of the tobacco into the bowl, you are over-doing it.
The headaches and problems really will go away with continued practice. Keep at it and good luck. The slow burn of a nice flake is a noticeably different experience than smoking loose cut tobacco and is worth some effort.