Add a small amount of white to one of the plastic cups. Mix with a tiny bit of water to make the paint more fluid.
Place some blue paint in a second clean cup and then some green paint in a separate plastic cup. The ratio of blue to green should be around 2 to 1. Use the filbert brush or a clean popsicle stick to stir the paint. Work quickly because acrylic paint is quick drying.
Apply some paint to the paper to see how the color looks.
Adjust the color by adding more blue or green to the mixture.
Add a dab of cadmium yellow to increase the teal effect. The yellow actually deepens the hue of the mixture by reacting with the blue to create a green and with the green to create a yellow green. A small amount of white can also be added at this time, if a lighter color is desired -- or add a minute quantity of black to create a slightly darker shade.
Add a small amount of acrylic medium to increase the flow of the mixture. The addition of water will not increase flow.