* Texture: The key to waves is having some texture in your hair. Straight, fine hair is very difficult (though not impossible) to train into waves.
* Length: Your hair needs to be short enough to lay down and form the wave pattern, but long enough to be manipulated with a brush. A good starting point is between 1/4 inch and 1/2 inch.
* Curl Pattern: Hair with a natural slight wave (2A-2C) or curl pattern (3A-3C) typically forms waves easier.
* Thickness: Medium to thick hair is generally preferred, as it has more volume to create the wave pattern.
While hair with a natural wave or curl is best, people with straighter hair can still achieve waves with dedication, the right products, and a consistent routine.