Experiment with making a sound!

Wet your lips, bring your lips together as if saying the letter "m", relax your jaw and keep your upper and lower teeth slightly separated, firm the corners of your mouth like a slightly puckered smile, create an air stream through the center of your lips. This will create a buzz, and hear the buzzing doing this without an instrument helps build the embouchure. Brass players use this exercise to practice or warm up without their instruments.