When the Holy Prophet (Sallallahu alaihi wa sallam) would bathe, He would first wash His hands, then make ablution as it is made for offering Salaat.
Then He would wet His fingers and wet the roots of His hair with them.
Then three times He would pour water on the head.
Then He would pour water over all His body.
(Sahih Bukhari, Hadith No. 248)
