I grew my hair long when i was younger, almost down to my ass. It started out very wavy and wanted to curl up in the back and on the sides. I kept growing it though and eventually it all straightened out. I think maybe it was the length of the hair and the weight of it. I remember never blow drying my hair also.. that will cause it to frizz. And dont brush it while wet... use a broad tooth comb. If you just have very very curly hair (Like Slash of Guns & Roses) you may just want to grow it out all poofy and add a chemical relaxer.