The waterbrush tip size determines how much water is dispensed with each brush stroke. Fine brushes release less water per stroke and are good for detail work while large brushes are suited for covering larger areas.
Claude Monet - Subtle contrast between red and green, and creation of green out of grays using relative colors, mid tone through drastic high and low temperature balance, canvas shape allows a lot of background with a close foreground.
Painting a watercolor sunset is an easy beginner's exercise as it doesn't contain too many drawn-in details. You can create a beautiful, multi-hued wash that mimics the vibrant colors of a sunset with (Step Exercises Tips)