IME, one of the most important techniques for a successful straightening experience is using an insanely moisturizing deep conditioner, which will go a long way in achieving optimal results. This thread will further illuminate my point and provide essential information:
https://www.longhaircareforum.com/t...et-for-perm-straight-hair-in-one-pass.431336/
I also garner good results when I limit my post-DC product usage. To address your questions
@CurlyMoo, I'm not sure why limited pre-straightening products are more effective. I only know how my hair, and some other people's hair, have responded when we allowed our paranoia concerning heat damage to run free. IME, too many layers of product is a guaranteed recipe for poufy, stiff hair. To that end, all I use is a light, silk protein-laden leave-in and heat protectant. Twice, I lightly sealed with grapeseed oil after the leave-in, but that produced hair that was way too straight for my liking (my hair is low density and I felt bald). I believe the key lies with the efficacy of one's deep conditioner - it should be so good, so highly moisturizing that anyone in the vicinity will receive secondhand moisture from the fumes. And, all of its goodness is more than sufficient to protect against heat damage while providing excellent results. This is why the DC is a crucial aspect of straightening. At least, that's my theory of it all.
However, the most important tweak to my straightening routine has been doing the entire process while seated in a mirrored, well lit, comfortable area. IMO, standing in front of a bathroom mirror for protracted necessities/styling is unnecessary torture that leads to fatigue and over-heating, which causes impatience and bouts of sweating...which in turn causes exasperation, haste and reversion. The more comfortable I am, the better the process goes. This is why I always advocate for women to construct a beauty station for themselves.