According to the practice of the Prophet (saw), the correct way to perform Ghusl is:
1. Wash both hands three times,
2. Wash the private parts,
3. Make a complete wudu (ablution) like the one made for prayer.
4. Rub water through one's hair three times, letting the water reach down to the roots of the hair, (yes, girls...this means ruining that perfect hairdo!)
5. Pour water over the entire body, beginning with the right side, then the left, washing under the armpits, inside the ears, inside the navel, inside the toes and whatever part of the body can be easily rubbed. This account is based on the following report from 'Aishah:
"When the Prophet (saw) took his bath after
sexual intercourse, he would begin by washing his hands. Then he would
pour water from his right hand to his left and wash his sexual organs,
make the ablution for prayer, take some water and put his fingers to the
roots of his hair to the extent that he sees that the skin is wet, then
pour water over his head three times and then over the rest of his
body." -Related by al-Bukhari and Muslim.
Ghusl For Women:
A woman performs Ghusl just as a man does, except that if she has plaited/braided hair she does not have to undo it, provided that the water can reach the roots of her hair. Umm Salamah said,
"O Messenger of Allah, I am a woman who has closely plaited/braided hair on my head. Do
I have to undo them for ghusl after sexual intercourse?" He said, "No, it is enough for you to throw three handfuls of water on your head and then pour water over yourself. After doing this, you shall be cleansed." Related by Ahmad, Muslim and at-Tirmidhi.