This practice will help to paint around the edges of shapes.
Paint simple shapes on your dry piece of watercolour paper.
Paint around these shapes in a different colour. Use different sized brushes - a smaller for more detailed areas and a larger for filling out larger areas.
Ensure you have enough blue paint (about 50/50 water to watercolor). Keep the blue area moist to pick up where you left off.
Get really close to each shape without touching the first shape.