'Magnolia' (watercolors 11x14") done about ten years ago when I was still learning to handle paint, was a breakthrough for me. Magnificent magnolias were in bloom in a friend's garden, and I had attempted to paint one blossom. I was not at all pleased with the results. In my frustration and disappointment, I took the painting to the bathtub, washed the colors out and let the sheet dry. When it was a barely wet to the touch, I went over part of the painting wet on wet and added back the colors slowly adding details only to the flower and nothing else. I left the lower right corner pretty much alone except for splattering some paint on it. After all these years, I still struggle to leave part of white of the paper alone, and often have to resort to washing the paints off to get the desired effect. I guess therefore my technique is paint, wash, and paint again :)
I have been asked about how I painted the textures and 'underwater look' in my earlier post 'Painted Pebbles.' After drawing the rocks, I rubbed lightly a white crayon on parts of the rocks and rest of the drawing. The wax in the crayon resists watercolors and the white shows through. For algae, I dipped a dry sponge in various colors and tapped it on some of the rocks. I used a toothbrush to splatter colors around. One fun technique was to transfer pictures using gesso which is explained here very clearly. I cut a small piece of sunday color comics and used regular gesso (matte) for that. Hope this is helpful.