I used to use Motions Nourish Leave-in Conditioner and Chi Silk Infusion Reconstructing Complex to blowdry and then Proclaim Bergamot Emerald grease to flat-iron. It got my hair really straight and my hair did not revert for weeks (only washed my hair every 2-4 weeks).
Just a couple of days, I tried only Ultra Sheen Setting Lotion to blowdry my hair. Then I flat-ironed with no additional products. I like doing this WAY better than using the grease. It left my hair feeling softer, lighter, and more moveable. When I used the flat-iron, it didn't make that scorching frying sound and it didn't get my hair hot like it did with grease. So I only used one product, which was the setting lotion, as a heat protectant! Next time, I plan on rollersetting instead of blowdrying.