In order to get bouncy curls and a voluminous look, you can use a hair straightener as opposed to a curling iron. For the best results, you have to practice often.
Preparation and pointers
Always start on dry hair. Although there are straighteners that promise results when you use them as your hair is still wet, start on dry hair. Wet or damp hair does not curl well. In case you are using a blow dryer to get your hair dry, use mousse as it adds volume to the hair thus avoiding the flatness that makes hair look thin. Additionally, apply heat protectant on your hair before you start straightening it. This protects your shafts against heat damage. For those with wavy or straighter hair, spraying the product all over your head then combing through to distribute it evenly will work. For thicker hair, however, it would be best to work in sections, spraying and combing through with a wide-toothed comb. The actual straightening is done in sections as well and requires a thin flat iron. Once you create a top bun, section from the bottom and straighten and curl in layers.
There are different approaches to curling the hair. For soft waves, the technique requires clamping down the hair about halfway at the shaft by making a half turn by turning the flat iron on its back and running it through the shaft at that angle. This is known as a flick. For curls, one has to clamp the hair at the root but not too close to the scalp to avoid burning yourself. Make a half turn by turning the flat iron on its back and running it through the whole hair shaft at that angle. For both techniques, slowly running the flat iron achieves a tighter wave or curl while a faster run achieves a loose one. Additionally, for more pronounced curls on either flicks or curls, you ought to do a full turn which includes making a round loop where the hair goes around and over itself. You can also alternate the direction of curls to see what works best for your hair.
Some hair types do not easily hold curls. The solution to this is to put hairspray on every section just before you flat iron. Do not use too much as it leads to a crunchy and stiff look. Just spray it on and use whichever curling technique works best for you. The smaller the section, the tighter your curls will be.
Sections that are more than two inches wide yield looser curls. You can experiment with different section sizes on different parts of the head. The front could have tighter curls while the back could have looser ones to create volume. In addition to this, you can lightly mist the hair after curling so as to hold the curls all day.