Watch as SumetraReed demonstrates how to achieve fluffy, smooth, straight hair with one pass of the flat iron!  
My major heat styling tips?  Only blow dry damp hair (not soaking wet hair) and definitely use the chase method (as demonstrated in this video) during the flat ironing process (wherein you chase a fine tooth comb with the flat iron) for more effective straightening. These tips, along with a good heat protectant will really help in the prevention of heat damage.  

What are your heat styling tips?