I've had trouble using a flat irons. Have bought 2 & returned them. Maybe I should try a Chi but they seem so $$$$. Everytime I use one, my hair gets incredibly puffy with static! I totally have to re-wash it. Anyway, I don't have wavy or curly hair and not straight, just nasty semi-wavy. So I have to use salon priced shampoos, conditioners and very strong styling products and a round brush. That's what smooths my nastiness & frizzies out. I can never let it air dry.
So, I would love to try a flat iron occasionally, if it made it look better, not worse!!