I've had great success with a blowdryer and a flat iron, but the trick for me has been to use a good leave in, and blow dry my hair when it's still very wet and pliable. If you try to blow dry natural hair and it's reverted too much, you get knots and breakage. I recently blew my hair out so I could trim it, and it came out pretty smooth. I don't straighten very often due the humidity in Miami though.
I shampoo'd with a non sulfate shampoo, conditioned with Pantene S&S, then used Mizani thermal protector, though I forget the name. I sprayed the Mizani on each section before I blow dryed, and used my Denman brush to make sure I blew it nice and straight. After that, I flat ironed with my ceramic iron, added a little Kemi Oyl, and wrapped my hair. I think the wrap is the most important part of the flat iron process, b/c it sets the hair and makes it very silky.
Anyways, HTH. I snapped a pic of it, couldn't post the pic, but here's the link:
http://us.a2.yahoofs.com/users/43c9633fzc1ff9422/fa33/__sr_/95fbre2.jpg?phA2SzDB7Wd97Occ