There are many skills you will employ as a writer. The most important is finishing what you start.
It doesn't matter how brilliant your prose is or how likeable your characters are. It doesn't mean a thing if your story is the most creative idea ever or your dialogue is stunning. If you don't finish it won't matter.
It sounds simple. It is not. Starting at the beginning of a story and working through to the end (whether you're writing a 5k short or an 80k novel) is hard. Start developing that skill now.
Too many writers get “I-got-a-better-idea-itis”. Been there and done that. I spent over ten years starting various projects, getting stuck and then starting something new. As a writer you have to learn to push through the difficult parts. Sometimes that will mean skipping over something until you figure out why it's not working. (That approach is easier when the project in question is a novel.) Sometimes it will mean sitting and staring at the computer screen (or piece of paper if you prefer to write things long-hand) for hours until the words flow out again.
Finish what you start. It will do wonders.