Well, It is already mentioned that one must write to get into the habit.
But If You want to become a good writer. You must go through the literature filled with good writings. Start reading the forefather of literature. Doesn't matter which country or nation because after reading writers from all over the world not much but even in little autobiographical excerpt I realized THEY HAVE ONE THING COMMON and that is HUMBLENESS.
SO Write and Read or vice versa!!
I hope this helps :)