Even if you don't draw anime style here are some fun tips for watercolor sketching given by Hayao Miyazaki best known worldwide for Princess Mononoke, Spirited Away, The Wind Rises and is head of Studio Ghibli animation in Japan.
Hayao Miyazaki’s advice on how to use transparent watercolors in the booklet of the Ghibli Museum Sketching Set.
Title: My recommendation. Transparent watercolor is good.
“transparent watercolor has a strong habit”, “do not paint stickily and paint after wiping the extra paint and water off”, “paint thinly the bright part”, “had better not use white” (no tinting), “paint other color after under color has dried”, “let’s mix the color and use it.”
Light the wool which protrudes on a new painting brush. (singe the frayed ends on a new brush with a lighter)
Anything is fine for a water vessel.