How do you bleach your hair ?

To the girls that do it themselves, i've done it plenty of times and achieved a nice platinum blonde , i've learned 
what to use to help the process . 
some girls section their hair into 4 parts and do one by one . 
others start from the bottom of their hair then do the rest and work their way up slowly . 
Anyone have other different ways ? This time im thinking of doing it by parts