@marina—I think it’s a great exercise to mimic writers you love, actually. We’re caught up with the idea of being original too early. Tom Stoppard essentially imitated different authors for his first ten plays. After that, he was ready to write in his own voice.
Nighttripper—try finding passages in books that get you to care about characters quickly. See if you can imitate what the authors do. Don’t worry about being original—it’s just a writing exercise.
Also, think about where your characters are, and who they are, but also where they’re going. Presumably they should change or learn about themselves (or we should learn about them) as they encounter challenges in your story.
Try to take things you notice about people in life and include them in your character descriptions. Try writing descriptions of people you know. Can you capture elements of what make the people interesting in writing? Be specific, as specific as you can.
Also, as you get to writing, let different things happen to your characters. See how they respond. Don’t be afraid to try anything out. You have plenty of time to edit later.