Step 1: Pick your poison- The perfect blowout starts in the shower, with the correct shampoo and conditioner for your hair type, ie: if you have straight/flat hair, use lightweight products. I use Garnier Body & Volume Fructis which can be found at CVS for $3.99.
Step 2: Pre-dry- Before a round brush even touches your hair, press a towel to damp hair (paper towels supposedly work best to eliminate frizz) and apply a serum that offers heat protection. I like Nexxus Heat Protexx which can be found at Walgreens for $11.99. Start up the blow dryer on low heat and dry using your fingers as a comb until hair is 75% dry, to reduce the amount of heat damage on your hair.
Step 3: Time for the round brush- Take 2" sections of hair (starting from the front) and wrap around a round brush, and pull down while pointing the dryer at the section of hair (at this point, the drier is hot). It is important to maintain tension in the brush as you pull down. In order to get my hair so straight I don't have to use a straightener, I use the nozzle attachment in the image below. To create some lift, dry the pieces at the crown forward, and brush away from your face.
I hope these tips give you luscious locks and you end up looking like this...