Writer's block

I love to write. I love putting together words to make stories people are interested in. I love forming a sentance that sounds just right. I just....I love it. And it's what I'm best at.
The thing is, I never know what to write about. I'll get an idea for an opening of a story, or a character, or just some small part. But I never know where my stories are going. I can never figure out what happens next. My stories tend to fall apart very quickly, because I decide they don't turn out well at all.
So, how to get over my writer's block? Possibly I just need to focus more. Make myself actually think things through. That way I know what the general plan is before I start writing. That'd probably would help a lot. Other than that...I really don't know. Maybe steeping away from the story for a bit would be all I need.
Either way, if I actually start a story I like, I promise to let you know.
Callie