For me what's worked is using oil. I can't just be easy on products and think my hair will last and not revert. I use CD Hair Butter as I airdry and then use a creamy lotion type product on the length (like Hair Milk). Then as I flatiron, I use either a serum heat protectant or a spray heat protectant. I've found the degree of heat doesn't make much difference. If I use high heat and get it super straight, it stays that way. Otherwise, if I use lower heat and don't get it super straight, it stays that way, too. Usually the only reversion issue I have is my roots. The rest stays straight till I wash again.