Hana Kamkar, a famous singer, removed her hijab

Don’t be afraid to make some noise as your warm up. Let your voice wander up and down its range. Then move onto humming, or perhaps do some gentle lip rolls or tongue trills. Only once you feel like your face, mouth and voice are loosening should you start singing actual notes. The whole process should take between 10 and 20 minutes (and don’t skimp.)