How to be better at texting people?

All of my friends are always talking about their group texts and a lot of them text people all the time every night. I have an iphone, but I never have a reason to text anyone, boy or girl. I don't know how to start a conversation over text, and I have nothing to say. My friends never seem to have this problem. Whenever someone texts we talk for a few minutes, but then the conversation just sort of stops, and it never starts up again.
I'm really bad a group texts because I try to hard, and end up saying to much in them and it sounds awkward. It's not that I say something awkward, I just don;t know how to keep up a convo over text.
I do not have this problem in real life at all. The hardest part for me is starting a conversation. How do I begin to talk to someone over text?

What are reason to text people? How do I keep a conversation going? How do I text boys that I like but don't know super well yet?
I know there are some master-texters out there!

Conversations don't have to go on forever.