Is it ok to have my sister dye my hair or should i go to a salon?

Personally i would go to a salon...im talking from experience i once dyed my boyfriends sisters hair. She had red hair and wanted to dye it black so she brought me the supplies and everything and i was doing a pretty good job i thought until the bottle ran out of hair dye and i was only half way done! so i did my best to hide it but half of her hair was gorgeous black and the other half was like black with reddish spots!!! i think you should go to a salon unless your sister knows how to dye hair :)