Singing is more than making noise. It's about maintaining a loose, free posture. The more free your body is, the more the air will be able to flow through your throat, ribs and face! Here are 3 of my favorite warm up to invigorate your posture before making any sounds.
Shoulder Rolls: roll em back, roll em forward. Do both at the same time, or isolate each. Remember never to lift your shoulder when you breathe. This will build that awareness.
Be a Rag Doll: Ooh, do I swear by this. Let you body hang/hunch forward, head gently falls forward, arms hang with gravity. Slowly roll back up to standing posture slowly and gracefully.
Hoola Hoops: draw a circle with your hips as if you are balancing a hoola hoop. Flexibility in the abdominal area creates a freer breath and unlocks your posture.