Many talented writers don't make it because they let others convince them they won't, or can't. They lose faith in themselves, which is far worse than never getting published. Your characters will not become real to a reader until you give them a world in which to live. In other words, pay close attention to the weather, geography, etc. Also, let the reader know of the characters' emotional attachments to whatever is going on around them.
Emotion is the connection to everything, whether it's bad or good.
It's what makes a reader identify and remember. The process of that will teach you a lot. Also, read everything you can about writing there are many how-to books that explain plotting, characterization, and so on. Writing is a habit, like exercise. If one person's rejection can shatter your faith in yourself, you're in the wrong business.