For me, a higher heat usually works best. Just set yours a bit higher than usual. First, section off a piece of hair. Then clamp your straightener down & guide it down the length of your hair about an inch or so. Then rotate the straightener at 180? in the direction that you want the curl to go. Then move it down your hair shaft & release. Hope this helped.
you have straight hair that you are trying to curl, or the other way around? because if it's the straight hair to curl, use a curling iron or hot rollers for best results. My sister has stick straight hair and I have curly, so I have a bit of experience with both. if it's curly hair to be straightened, then get a relaxer and use it, not the flat iron. I used a flatiron 1 time, my hair looked like a bush. I strongly recommend you do not use a flat iron if your hair is curly.