If you're straightening your hair by dragging your flat iron downwards, then you're doing it wrong. This method causes hair to lose its body, resulting in flat, lifeless locks. It can also cause indents where the flat iron is placed by the roots if the hair is not elevated properly.
This technique helps prevent indentation marks from the straightener's plates, which usually occur when clamping the tool on strands that are hanging straight down. A fine-toothed comb should be used to detangle knots and guide the straightener (Hawkins used the ghd Eclipse Styler for this tutorial) along.
Before straightening, Hawkins recommends applying a heat protectant like L'Oréal Professionnel Mythic Oil or Moroccanoil Treatment to minimize damage. Applying heat to locks that aren't moisturized causes the hair cuticle to break.
If your hair is coarse or curly, be sure to separate into 1 to 2-inch sections to ensure an even and smooth finish. Finish by smoothing the crown area with a polishing wax or pomade like L'Oréal Texture Expert Lumi Contrôle.