What should i say to him??? Help?

i'm textin this guy, and one time he said that he had more better things to do then text. But he texts me at least once every other day, and he brings the conversations up. I want to start a conversatin, but what should i say to him?? "Hi?" hello, hey, chello, sup....what? i don't kno wat i should say...or what we should talk about and i need to know what to do asap. thanks:-)