I dont think it really makes that much difference how u dry it because the flat iron, especially a high end ceramic one, really smoothes it out. I think the key is not using anything on the hair to weight it down. Ive only used mine a couple of times, but I air dried in a ponytail and then flat ironed and it looked very nice.
When I went to the hair salon, she would wash, deep condition, come my hair straight down like a bowl all around my head and sit me under the dryer to partially dry,
then she would blow dry it and flat iron with a bump. Then she would wrap it, cover it in saran wrap and put me back under the dryer for about 10 minutes. After that she would comb it down to style, and it looked really good. Its the nicest my hair ever looked, like the box of a perm!
HTH!