First and foremost, I've found that DRY incubation seems essential. otherwise they end up sticky/gooey and often very wet at hatch. many have also gotten stuck because they can't turn properly, whether because of the goo or because of being too bloated from excess fluids.
with SFH I've taken to not putting them in lockdown until day 19, and that seems to have helped some as well.
but then again I dry incubate EVERYTHING, so haven't had as many problems as I've heard about from others.
I haven't had problems with early quitters tho, usually just wet hatches, even when dry incubation.
I dry-incubate as well, and have had good hatch rates with my SFH