Why is my hair always poofy and frizzy?

when i straighten my hair it just looks like a big poof ball( maily towards the ends). my straightener goes up to 400-410 so imm thinking its just my hair. it takes me like two damn hours to straighten my hair but im also new at it. i only sttaighten my hair like 2 times a month and i have rlly curly, frizzy.long, pretty thick hair :)