Why is my hair so unmanageable?

Everyday when I wake up my hair is like insane. It's curly and frizzy and I have to straiten it every morning. Even though I straighten it, it never stays straight, throughout the day it gets tangled and wavy and just gross looking. Ive tried different shampoos and conditioners and i'm caucasian so I don't think it's due to my ethnicity, I just don't know a lot about hair or what to do about it if anyone has any suggestions it would help