How can I curl already curly hair with a curling iron?

I already have curly hair, but it is more of a frizzy curly. Is there any tips or special techniques to curling my already curly hair with a curling iron to get a more defined look?

How can I curl already curly hair with a curling iron?

Aveda Be Curly Curl Enhancing Lotion - improve the look of curly or wavy hair,Intensifies curls, controls frizz %26amp; enhances sheen

or

Frizz ease-Blocks frizz all day

Instantly and dramatically transforms dry, frizzy hair into incredibly smoother, glossier, stronger hair immediately smoothes texture while delivering a layer of crystal-clear gloss for perfectly polished, frizz-resistant styles

Repels humidity to help prevent weather-related frizz

I've had experience of both products and if you have fine hair I'd go for the aveda and if you have thick or coarse hair go for the frizz ease. Heat treating won't stop the frizz!