The first thing you should do is to comb the tangles out of the hair before you wet it so the hair would wash easily and the tangles would not worsen. And then, wet your hair thoroughly under the shower. You can use either warm or cold water if you like, but for best results, you can wet your hair with warm water to open the scale-like cuticles of the hair and wash all the oil and dirt off. And then, you can rinse your hair with cold water afterwards to close the cuticles and add to the shine of your hair.