This is the audio exerpt of f spoken within a word. It may sound a little short or unclear, but that's exactly how it's in the real context. For more details, read the below explanation of pronunciation and listen example words that contain f by pressing the word buttons.
1. Break the airflow by touching your upper teeth with your lower lip.
2. Push the air through the interruption to produce an audible friction of the air.
3. Relax your vocal cords.