What can I do about my hair?

I am a guy with hair that is kinda long. I have really thick hair. My front hair is above my eyes. It naturally goes to the right. Sometimes girls ask if I straighten my hair because sometimes my hair can look really straight and nice. Other times when I wash my hair with the conditioner that my mom buys, my hair after when it drys gets ugly, hair turns into like a ugly-curly look(if that makes sense) and I don't have Curley hair. and it can look dried/poofy. So is there anything I can do to make my hair nice and smooth like it sometimes is? Please don't tell me something to get or do that will make my hair greasy... Cuz girls don't like greasy hair (: thank you!