Beginners often get caught up in subplots they find interesting, but don’t serve to propel the characters forward in any real way. Your story isn’t a well-cast ensemble sitcom. Focus diligently on one main plotline, and if you do decide to add subplot elements to your story, make sure they relate to the main story and help propel your character to his or her inevitable end.
That happened to me many times.I can't focus on one story, I jump to one story to another. I have three novels that I wrote when I was still young and thanks to my unfocus mind I haven't finish that novel.
And now I am in the process of writing a novel again. What I did now? I keep a notebook or index card with me. Wherever I go I bring it with me and I also have a copy in my tablet. That everytime I forget my story I look at it then write again.
