One way is to really dig deep into your characters' emotions and experiences. Understand them intimately and let that come through in your writing. Also, don't be afraid to show your own personality and passions in the words you choose and the way you construct sentences.
Well, to get more voice in your fiction writing, focus on being authentic. Write from the heart, use vivid and specific language, and don't hold back on expressing unique perspectives. Another thing is to experiment with different narrative styles and tones to find what suits your story best.