Here is a more detailed look how watercolors work:
The easiest way to activate your watercolors is by using a watercolor pen. You fill the pen with water, next squeeze a drop of water onto a kitchen towel and tap the brushes onto the towel as well. You might think this is not enough water on the brush, but less is more. You brush will contain plenty of water to activate the color.
Next, start with the lighter color first. Go with you brush over the color and you will see how the water will intensify the color. Always tab your brush of before you start with a new color to avoid cross termination. Watercolors, once activated with water, will react like regular watercolors.
If you are staying in the same color family, for example brown, you should start with the lightest one, like a beige and move towards the darkest one. In this case a cleaning of the brush in between is not necessary. You will blend all brown shades nicely together.
Should you have to much water on the brush, tab it of, otherwise the paper will soake it up and it will get really wavy.