Cool video about Chi Flat Iron, have a look:

This vid is on how to create a wavy natural look with a flat iron

My hair remains straight for a couple of hours & then gets wavy again. I've seen people having so sleek hair after straightening. Should I be using some kind of straightening serum or cream prior to straightening with iron? Can u guys recommend something that helps to keep the hair straight & sleek for a whole day? Thanks.